perf tools: Fix sample size bit operations

What we want is to count the number of bits in the mask,
not some other random operation written in the middle
of the night.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1306148788-6179-2-git-send-email-fweisbec@gmail.com
[ Fixed perf_event__names[] alignment which was nearby and hurting my eyes ... ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>