perf sched timehist: Enlarge default 'comm_width'

perf sched timehist: Enlarge default 'comm_width'

Current default value is 20 but it's easily changed to a bigger value as
task has a long name and different tid and pid.  And it makes the output
not aligned.  So change it to have a large value as summary shows.

Committer notes:

Before:

  # perf sched record
  ^C
  # perf sched timehist
  <SNIP>
    40602.770537 [0001]  rcuos/2[29]               7.970      0.002      0.020
    40602.771512 [0003]  <idle>                    0.003      0.000      0.986
    40602.771586 [0001]  <idle>                    0.020      0.000      1.049
    40602.771606 [0001]  qemu-system-x86[3593/3510]      0.000      0.002      0.020
    40602.771629 [0003]  qemu-system-x86[3510]           0.000      0.003      0.116
    40602.771776 [0000]  <idle>                          0.001      0.000      1.892
  <SNIP>

After:

  # perf sched timehist
  <SNIP>
   40602.770537 [0001]  rcuos/2[29]                         7.970      0.002      0.020
   40602.771512 [0003]  <idle>                              0.003      0.000      0.986
   40602.771586 [0001]  <idle>                              0.020      0.000      1.049
   40602.771606 [0001]  qemu-system-x86[3593/3510]          0.000      0.002      0.020
   40602.771629 [0003]  qemu-system-x86[3510]               0.000      0.003      0.116
  <SNIP>

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20161222060350.17655-1-namhyung@kernel.org
[ Split from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>