perf stat record: Synthesize stat record data

Synthesizing needed stat record data for report/script:
  - cpu/thread maps
  - stat config

Committer note:

New records generated on a perf.data file with this patch:

  $ perf report -D | grep PERF_RECORD_
  0x568 [0x28]: PERF_RECORD_THREAD_MAP nr: 1 thread: 29097
  0x590 [0x12]: PERF_RECORD_CPU_MAP nr: 1 cpu: 65535
  0x5a2 [0x40]: PERF_RECORD_STAT_CONFIG
  $

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Kan 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/1446734469-11352-5-git-send-email-jolsa@kernel.org


[ Adjusted wrt kernel PERF_RECORD_MMAP added when introducing 'perf stat record' ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>