perf report: Also do default setup for synthesized branch stacks

The 'perf report' tool will default to displaying branch stacks (-b
option) if they are present.  Make that also happen for synthesized
branch stacks.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1443186956-18718-11-git-send-email-adrian.hunter@intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>