perf hists: Enlarge pid sort entry size

perf hists: Enlarge pid sort entry size

The pid sort entry currently aligns pids with 5 digits, which is not
enough for current 4 million pids limit.

This leads to unaligned ':' header-data output when we display 7 digits
pid:

  # Children      Self  Symbol                    Pid:Command
  # ........  ........  ......................  .....................
  #
       0.12%     0.12%  [.] 0x0000000000147e0f  2052894:krava
  ...

Adding 2 more digit to properly align the pid limit:

  # Children      Self  Symbol                      Pid:Command
  # ........  ........  ......................  .......................
  #
       0.12%     0.12%  [.] 0x0000000000147e0f  2052894:krava

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
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/1466459899-1166-9-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>