perf trace: Add fallback definition of EFD_SEMAPHORE

perf trace: Add fallback definition of EFD_SEMAPHORE

glibc 2.17 is missing this on sparc, despite the fact that it's not
architecture-specific.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Fixes: 49af9e93adfa ('perf trace: Beautify eventfd2 'flags' arg')
Cc: <stable@vger.kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1391648435.3003.100.camel@deadeye.wl.decadent.org.uk
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>