perf stat: Add --table option to display time of each run

Add --table option to display time for each run (-r option), like:

  $ perf stat --null -r 5 --table perf bench sched pipe

   Performance counter stats for './perf bench sched pipe' (5 runs):

             # Table of individual measurements:
             5.379 (-0.176)
             5.243 (-0.311)
             5.238 (-0.317)
             5.536 (-0.019)
             6.377 (+0.823)

             # Final result:
             5.555 +- 0.213 seconds time elapsed  ( +-  3.83% )

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180423090823.32309-8-jolsa@kernel.org


[ Document the new option in 'perf stat's man page ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>