perf tools: Move branch option parsing to own file

.. to allow sharing between builtin-record and builtin-top later.  No
code changes, just moved code.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1432749114-904-9-git-send-email-andi@firstfloor.org


[ Rename too generic branch.[ch] name to parse-branch-options.[ch] ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>