perf script: Display stat events by default

perf script: Display stat events by default

If no script is specified for stat data, display stat events in raw
form.

  $ perf stat record ls

  SNIP

   Performance counter stats for 'ls':

            0.851585      task-clock (msec)         #    0.717 CPUs utilized
                   0      context-switches          #    0.000 K/sec
                   0      cpu-migrations            #    0.000 K/sec
                 114      page-faults               #    0.134 M/sec
           2,620,918      cycles                    #    3.078 GHz
     <not supported>      stalled-cycles-frontend
     <not supported>      stalled-cycles-backend
           2,714,111      instructions              #    1.04  insns per cycle
             542,434      branches                  #  636.970 M/sec
              15,946      branch-misses             #    2.94% of all branches

         0.001186954 seconds time elapsed

  $ perf script
  CPU   THREAD             VAL             ENA             RUN            TIME EVENT
   -1    26185          851585          851585          851585         1186954 task-clock
   -1    26185               0          851585          851585         1186954 context-switches
   -1    26185               0          851585          851585         1186954 cpu-migrations
   -1    26185             114          851585          851585         1186954 page-faults
   -1    26185         2620918          853340          853340         1186954 cycles
   -1    26185               0               0               0         1186954 stalled-cycles-frontend
   -1    26185               0               0               0         1186954 stalled-cycles-backend
   -1    26185         2714111          853340          853340         1186954 instructions
   -1    26185          542434          853340          853340         1186954 branches
   -1    26185           15946          853340          853340         1186954 branch-misses

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/1452077397-31958-3-git-send-email-jolsa@kernel.org
[ Rename 'time' parameter to 'tstamp' to fix build on older distros ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>