perf sched timehist: Add summary options

perf sched timehist: Add summary options

The -s/--summary option is to show process runtime statistics.  And the
 -S/--with-summary option is to show the stats with the normal output.

  $ perf sched timehist -s

  Runtime summary
                            comm  parent   sched-in     run-time    min-run     avg-run     max-run  stddev
                                            (count)       (msec)     (msec)      (msec)      (msec)       %
  ---------------------------------------------------------------------------------------------------------
                  ksoftirqd/0[3]       2          2        0.011      0.004       0.005       0.006   14.87
                  rcu_preempt[7]       2         11        0.071      0.002       0.006       0.017   20.23
                  watchdog/0[11]       2          1        0.002      0.002       0.002       0.002    0.00
                  watchdog/1[12]       2          1        0.004      0.004       0.004       0.004    0.00
  ...

  Terminated tasks:
                     sleep[7220]    7219          3        0.770      0.087       0.256       0.576   62.28

  Idle stats:
      CPU  0 idle for   2352.006  msec
      CPU  1 idle for   2764.497  msec
      CPU  2 idle for   2998.229  msec
      CPU  3 idle for   2967.800  msec

      Total number of unique tasks: 52
  Total number of context switches: 2532
             Total run time (msec): 218.036

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20161116060634.28477-5-namhyung@kernel.org
[ Add documentation from last commit, so that docs comes with the cset that introduces the feature ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>