perf tools: Remove unused _ALL_SOURCE define

Curious as to what this was for I looked at /usr/include/ and only some
python headers define this, and it ends up being to enable "extensions"
on some old OSes:

/* Enable extensions on AIX 3, Interix */

I guess we can remove this one safely.

Cc: Adrian Hunter <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: http://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/util.h

···
 #ifndef GIT_COMPAT_UTIL_H
 #define GIT_COMPAT_UTIL_H
 
-#define _ALL_SOURCE 1
 #define _BSD_SOURCE 1
 /* glibc 2.20 deprecates _BSD_SOURCE in favour of _DEFAULT_SOURCE */
 #define _DEFAULT_SOURCE 1