perf tools: Enhance the matching of sub-commands abbreviations

We support short command 'rec*' for 'record' and 'rep*' for 'report' in
lots of sub-commands, but the matching is not quite strict currnetly.

It may be puzzling sometime, like we mis-type a 'recport' to report but
it will perform 'record' in fact without any message.

To fix this, add a check to ensure that the short cmd is valid prefix
of the real command.

Committer testing:

  [root@quaco ~]# perf c2c re sleep 1

   Usage: perf c2c {record|report}

      -v, --verbose         be more verbose (show counter open errors, etc)

  # perf c2c rec sleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.038 MB perf.data (16 samples) ]
  # perf c2c recport sleep 1

   Usage: perf c2c {record|report}

      -v, --verbose         be more verbose (show counter open errors, etc)

  # perf c2c record sleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.038 MB perf.data (1...