perf record: Move mmap_pages to perf_record_opts

Tools being developed will need this to allow the user to override this
value.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-zydc1yhxfm0z35fuy95bsn1l@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --cc tools/perf/builtin-record.c
Simple merge

diff --cc tools/perf/perf.h
Simple merge