Incidentally, this introduces QMAKE_RESOLVED_BUNDLE, which can be used
to determine the path of the bundle wrapper itself as well as the
executable target.

This is necessary for a subsequent patch adding support for
-separate-debug-info on Apple platforms.

Change-Id: Ia11430026b8e3f171e5db6677b190b8356832805
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>