perf record: Intercept all events

The event interception we need to do in 'perf record' to create
a list of all DSOs in PERF_RECORD_MMAP events wasn't seeing all
events, make sure that happens by checking size agains
event_t->header.size.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1263586107-1756-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>