perf trace: Check if MAP_32BIT is defined

MAP_32BIT is defined only on x86... this means perf fails to build on
all other platforms.

Signed-off-by: Kyle McMartin <kyle@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20130905142947.GA25882@merlin.infradead.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>