'perf script' crashes currently when printing mixed trace points and
other events because the trace format does not handle events without
trace meta data. Add a simple check to avoid that.

  % cat > test.c
  main()
  {
      printf("Hello world\n");
  }
  ^D
  % gcc -g -o test test.c
  % sudo perf probe -x test 'test.c:3'
  % perf record -e '{cpu/cpu-cycles,period=10000/,probe_test:main}:S' ./test
  % perf script
  <segfault>

Committer testing:

Before:

  # perf probe -x /lib64/libc-2.28.so malloc
  Added new event:
    probe_libc:malloc    (on malloc in /usr/lib64/libc-2.28.so)

  You can now use it in all perf tools, such as:

	perf record -e probe_libc:malloc -aR sleep 1

  # perf probe -l
  probe_libc:malloc    (on __libc_malloc@malloc/malloc.c in /usr/lib64/libc-2.28.so)
  # perf record -e '{cpu/cpu-cycles,period=10000/,probe_libc:*}:S' sleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.023 MB perf.data (40 samples) ]
  # perf script
  Segmentation fault (core dumped)
  ^C
  #

After:

  # perf script | head -6
     sleep 2888 94796.944981: 16198 cpu/cpu-cycles,period=10000/: ffffffff925dc04f get_random_u32+0x1f (/lib/modules/5.0.0-rc2+/build/vmlinux)
     sleep 2888 [-01] 94796.944981: probe_libc:malloc:
     sleep 2888 94796.944983:  4713 cpu/cpu-cycles,period=10000/: ffffffff922763af change_protection+0xcf (/lib/modules/5.0.0-rc2+/build/vmlinux)
     sleep 2888 [-01] 94796.944983: probe_libc:malloc:
     sleep 2888 94796.944986:  9934 cpu/cpu-cycles,period=10000/: ffffffff922777e0 move_page_tables+0x0 (/lib/modules/5.0.0-rc2+/build/vmlinux)
     sleep 2888 [-01] 94796.944986: probe_libc:malloc:
  #
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20190117194834.21940-1-andi@firstfloor.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>