perf test: Add test for the evlist mmap routines

This test will generate random numbers of calls to some getpid syscalls,
then establish an mmap for a group of events that are created to monitor
these syscalls.

It will receive the events, using mmap, use its PERF_SAMPLE_ID generated
sample.id field to map back to its respective perf_evsel instance.

Then it checks if the number of syscalls reported as perf events by the
kernel corresponds to the number of syscalls made.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>