Adding the cpu_map event to pass/store cpu maps as data in
a pipe/perf.data.

We store maps in 2 formats:
  - list of cpus
  - mask of cpus

The format that takes less space is selected transparently in the
following patch.

The interface is made generic, so we could add the cpumap event data
into another event in the following patches.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Tested-by: NKan Liang <kan.liang@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1445784728-21732-8-git-send-email-jolsa@kernel.org
[ cpu_map_data_cpus -> cpu_map_entries, cpu_map_data_mask -> cpu_map_mask ]
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>