Move perf_mmap__put() from tools/perf to libperf.

Once perf_mmap__put() is moved, we need a way to call application
related unmap code (AIO and aux related code for eprf), when the map
goes away.

Add the perf_mmap::unmap callback to do that.

The unmap path from perf is:

  perf_mmap__put                           (libperf)
    perf_mmap__munmap                      (libperf)
      map->unmap_cb -> perf_mmap__unmap_cb (perf)
        mmap__munmap                       (perf)

Committer notes:

Add missing linux/kernel.h to tools/perf/lib/mmap.c to get the BUG_ON
definition.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-8-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>