Maemo: Don't unify packaging metadata between targets as rigorously.

This allows people to do external changes to their files without
Creator overwriting them.

Change-Id: I71fc7cf6dabb9a61762992b8c01f971f563e17ab
Reviewed-on: http://codereview.qt.nokia.com/12


Reviewed-by: Tobias Hunger <tobias.hunger@nokia.com>