macosx_application: fix file opening on OS X 10.9 (hopefully)

File opening through Finder, apparently drops `--psn` arguments on Mavericks
and just uses no args. Modify the code to account for that case.

This wasn't tested on 10.9 itself (I don't have a paid dev account), but it
*should* work if I understood the problem correctly.
macosx: always active bundle path lookup if cocoa is active

This is not really something you want to disable anyway. If there is no bundle
the code already does it's falbacks anyway.