perf script: Align event name properly

perf script: Align event name properly

Adding code to align event names, so we get aligned output in case of
multiple events with different names.

Before:
  $ perf script
  :13757 13757 163918.230829: cpu/mem-snp-none/P: ffff88085f20d010
  :13757 13757 163918.230832: cpu/mem-loads,ldlat=30/P:     7f5a5f719f00
  :13757 13757 163918.230835: cpu/mem-loads,ldlat=30/P:     7f5a5f719f00
  :13758 13758 163918.230838: cpu/mem-snp-none/P: ffff88085f4ad810
  :13758 13758 163918.154093: cpu/mem-stores/P: ffff88085bb53f28
  :13757 13757 163918.155264: cpu/mem-snp-hitm/P:           601080
  ...

After:
  $ perf script
  :13757 13757 163918.228831:       cpu/mem-snp-none/P: ffffffff81a841c0
  :13757 13757 163918.228834: cpu/mem-loads,ldlat=30/P:     7f5a5f719f08
  :13757 13757 163918.228837: cpu/mem-loads,ldlat=30/P:     7f5a5f719f08
  :13758 13758 163918.228837:       cpu/mem-snp-none/P: ffff88085f4ad800
  :13758 13758 163918.154093:         cpu/mem-stores/P: ffff88085bb53f28
  :13757 13757 163918.155264:       cpu/mem-snp-hitm/P:           601080
  ...

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: David Ahern <dsahern@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Noel Grandin <noelgrandin@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1452158050-28061-9-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>