[Qt] Unify qtFeatureDefaults code paths

[Qt] Unify qtFeatureDefaults code paths

There's no reason to run qmake on features.prf directly anymore, as we
can selectivly run configure tests in the project file now.

https://bugs.webkit.org/show_bug.cgi?id=90461

Patch by Oswald Buddenhagen <oswald.buddenhagen@nokia.com> on 2012-07-06
Reviewed by Tor Arne Vestbø.

* Scripts/webkitdirs.pm:
(qtFeatureDefaults):
* qmake/configure.pri:
* qmake/mkspecs/features/features.prf:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@121963 268f45cc-cd09-0410-ab3c-d52691b4dbfc