[Qt] Fix library linking order
https://bugs.webkit.org/show_bug.cgi?id=105818

Some Qt libraries are linked before the private static libraries
that depend on them which results in QtWebKit failing to link.

Copy Qt module dependencies from QT to QT_PRIVATE when creating
module to ensure the Qt libraries are linked after the private
static libraries that depend on them.

Patch by Jonathan Liu <net147@gmail.com> on 2013-01-03
Reviewed by Tor Arne Vestbø.

* qmake/mkspecs/features/default_post.prf:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@138707 268f45cc-cd09-0410-ab3c-d52691b4dbfc