perf tools: Parse tracepoints with '-' in system name

Trace events potentially can have a '-' in their trace system name,
e.g. kvm on s390 defines kvm-s390:* tracepoints.
We could not parse them, because there was no rule for this:
  $ sudo ./perf top -e "kvm-s390:*"
  invalid or unsupported event: 'kvm-s390:*'

This patch adds an extra rule to event_legacy_tracepoint which handles
those cases. Without the patch, perf will not accept such tracepoints in
the -e option.

Signed-off-by: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Link: http://lkml.kernel.org/r/1398440047-6641-2-git-send-email-yarygin@linux.vnet.ibm.com


Signed-off-by: Jiri Olsa <jolsa@kernel.org>