perf tools: Remove obsolete defines

perf tools: Remove obsolete defines

The _XOPEN_SOURCE* defines are not really needed on Linux and
it's not like we'll port this to AIX ;-)

The define also broke the build with gcc 4.4.1:

 CC util/trace-event-parse.o
 In file included from util/trace-event-parse.c:32:
 util/util.h:43:1: error: "_XOPEN_SOURCE" redefined

So remove them.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>