Sounds like a compiler bug, but to silence it, initialize those
variables to NULL.

Noticed on:

Target: x86_64-alpine-linux-musl
Configured with: /home/buildozer/aports/main/gcc/src/gcc-5.3.0/configure
--prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info
--build=x86_64-alpine-linux-musl --host=x86_64-alpine-linux-musl
--target=x86_64-alpine-linux-musl --with-pkgversion='Alpine 5.3.0'
--enable-checking=release --disable-fixed-point --disable-libstdcxx-pch
--disable-multilib --disable-nls --disable-werror --disable-symvers
--enable-__cxa_atexit --enable-esp --enable-cloog-backend
--enable-languages=c,c++,objc,java,fortran,ada --disable-libssp
--disable-libmudflap --disable-libsanitizer --enable-shared
--enable-threads --enable-tls --with-system-zlib
Thread model: posix
gcc version 5.3.0 (Alpine 5.3.0)

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-zyvsjvbl45o7hzcuz78wu2xi@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

This one can be safely defined to be Elf64_Nhdr, as it is in elfutils's
libelf, but not on musl libc, as both Elf64_Nhdr and  Elf32_Nhdr have
the same layout.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-w8z8614l03lc8bip4ijbywbt@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

All we need from it is already conditionally defined, and this header
file is not present in older systems, so ditch it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-3jxpz9gwahk4e7ltqtnr1rjg@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-6qkuhv2mrcxmpy5sasc3c9tf@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

On systems where sysconf(_SC_LEVEL1_DCACHE_LINESIZE) is not available,
such as musl LIBC and Android's bionic libc.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Chris Phlipot <cphlipot0@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-772obxzby758g7m2wmzcejxz@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Those kernel files were being directly accessed, which we're not
allowing anymore to avoid that changes in the kernel side break tooling.

Warn if these copies drift from the original files.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Eric Auger <eric.auger@linaro.org>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Yunlong Song <yunlong.song@huawei.com>
Link: http://lkml.kernel.org/n/tip-mnopguymhnwzjhw3mowllvsy@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Noticed while making a copy of these files to tools/ where those kernel
files were being directly accessed, which we're not allowing anymore to
avoid that changes in the kernel side break tooling.

Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Eric Auger <eric.auger@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-82thftcdhj2j5wt6ir4vuyhk@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-ogtjqc0hxm961djgiwboe2q7@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Not used anymore, IIRC it was for useless PROC_FS_MAGIC procfs checks,
but those are long gone.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-v027did3kvj0vz7bofgzkw29@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Which is just a wrapper for sys_getcpu and is not present in at least
musl libc.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-kblef7svmhr0g93kkx78envg@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

To allow the build to complete on older systems, where those files are
either not uptodate, lacking some recent additions or not present at
all.

And check if the copy drifts from the kernel.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-3jz31pz4nw526uko5da9e7o3@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

The prototype for epoll_wait() is available in older distros, so use it
instead of epoll_pwait() (removing the last NULL arg, the sigmask,
makes it the same thing anyway) to avoid breaking the build.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-pwiwizloxt0jujy8em80qut3@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

To allow the build to complete on older systems, where those files are
either not uptodate, lacking some recent additions or not present at
all.

And check if the copy drifts from the kernel.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-sxf7rpow2blsno5f7t6n0sqz@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

To allow the build to complete on older systems, where those files are
either not uptodate, lacking some recent additions or not present at
all.

And check if the copy drifts from the kernel, as in this synthetic test:

    BUILD:   Doing 'make -j4' parallel build
  Warning: tools/include/linux/bpf.h differs from kernel
  Warning: tools/include/linux/bpf_common.h differs from kernel

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-5plvi2gq4x469dcyybiu226q@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

We can't access kernel files directly from tools/, so copy the required
bits, and make sure that we detect when the original files, in the
kernel, gets modified.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-z7e76274ch5j4nugv048qacb@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

We shouldn't use headers from the kernel sources directly, instead we
should use the system's headers or in cases where that isn't possible,
like with perf_event.h, where the introduction of kernel features such
as perf_event_attr.{write_backwards,sample_max_stack} and
PERF_EVENT_IOC_PAUSE_OUTPUT take some time to become available in
/usr/include/linux/perf_event.h we need a copy.

Do it and check for source code drift, emitting a warning when changes
are detected.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-v6aks5un3s5pehory6f42nrl@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

As it uses PERF_REGS_MAX, fix it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-2t232w0kcqu97xod8t2at2h0@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Since these files use __maybe_unused, and that is defined in
linux/compiler.h, include it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-1llbf59ut6xon6ti88jm0n9j@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

To make it portable to non-glibc systems, that follow the XSI variant
instead of the GNU specific one that gets in place when _GNU_SOURCE is
defined.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-bozcszy93tpgw9ad6qm3dhpx@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Better to whitelist it for libraries that require it (glibc) than
blacklist it with the ones that don't (uclibc, musl libc, etc).

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Brodkin <Alexey.Brodkin@synopsys.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-52ih0m63a2n63tanpy6yj682@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

To make it portable to non-glibc systems, that follow the XSI variant
instead of the GNU specific one that gets in place when _GNU_SOURCE is
defined.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-mixgnh3iyajuqogn2opsocdy@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

To make it portable to non-glibc systems, that follow the XSI variant
instead of the GNU specific one that gets in place when _GNU_SOURCE is
defined.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-c1gn8x978qfop65m510wy43o@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

They were in tools/include/linux/kernel.h, requiring that it in turn
included stdio.h, which is way too heavy.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-855h8olnkot9v0dajuee1lo3@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

So that we don't have to carry a string.h header in evsel.h

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-2lwpm2aytdvvgo626zuat6et@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

The cache.h header doesn't use any of the definitions in some of the
headers it includes, ditch them and fix the fallout, where files were
getting stuff they needed just because they were including it, sometimes
not using what it really exports at all.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-l6r2bmj8h1g3e01wr981on0n@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

It uses isatty(), so needs unistd.h, include it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-ivwuz8f68tb3sdcpguo9wmvx@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Another case of a file using definitions and getting them by chance,
from indirect header inclusion, fix it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-o3l1vi4gw2w6xyc6z4ig938s@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

It uses poll() but was getting the needed header by chance, do it
explicitely.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-76b3c5imnl6p69j4lqewzu9l@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

It was getting all sort of needed stuff by sheer luck, via indirect
includes, fix it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-tvjgo39t8k0ye6dntv3knran@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

No need to include stdio.h from quote.h, also forward declare strbuf.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-k3kbcxhctpxvz6ckve3kv6c1@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

We were only indirectly and by luck getting types, etc needed for this
file, fix it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-gr8ejvzm7ojk6zwpeplyx9zu@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

And remove the empty tools/arch/x86/include/asm/unistd_{32,64}.h files
introduced by eae7a755 ("perf tools, x86: Build perf on older
user-space as well").

This way we get closer to mirroring the kernel for cases where __NR_
can't be found for some include path/_GNU_SOURCE/whatever scenario.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-kpj6m3mbjw82kg6krk2z529e@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

We should try avoiding that perf.h header, it includes way too much
stuff, making it difficult to use things like setting _GNU_SOURCE only
on a small set of headers.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-lb6eg9w1kzrwhv0gm3ho0h54@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

These were only defined if _GNU_SOURCE was set in older glibc versions,
check that and provide the defines in such cases.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-b8esouhpg4tk6vi4n3d7ipch@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

This one was only defined if _GNU_SOURCE was set in older glibc
versions, check that and provide the define in such cases.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-ilsgsysr6s3mru7rf2befnu5@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-dfcynqzvecsu55zmpxub9jgv@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Cc: David Ahern <dsahern@gmail.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-48qbfv7tqs8n8ey74lbyfjtq@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

The tools so far have been using the strerror_r() GNU variant, that
returns a string, be it the buffer passed or something else.

But that, besides being tricky in cases where we expect that the
function using strerror_r() returns the error formatted in a provided
buffer (we have to check if it returned something else and copy that
instead), breaks the build on systems not using glibc, like Alpine
Linux, where musl libc is used.

So, introduce yet another wrapper, str_error_r(), that has the GNU
interface, but uses the portable XSI variant of strerror_r(), so that
users rest asured that the provided buffer is used and it is what is
returned.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-d4t42fnf48ytlk8rjxs822tf@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Don't handle some flags only if they have its defines in headers at
time of building, define what is missing.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-wgjxeidwpowrvqgrxr080k6u@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Don't handle some flags only if they have its defines in headers at
time of building, define what is missing.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-pgoxanv1y6hfcnryxawzuskl@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>