Such as CentOS5, where such define is not present in elf.h.

This file, genelf.c, wasn't being built for several systems, because
it mistakenly was conditional on some DWARF features, now that it
is just needing libelf, after "perf jit: Enable jitdump support without
dwarf" it fails.

So, as preparation for "perf jit: Enable jitdump support without dwarf",
conditionally define it, if not available.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Maciej Debski <maciejd@google.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-k09qay1cmr0l3fzprmztzy3o@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>