Switch QtWebKit to GStreamer 1.0.
https://bugs.webkit.org/show_bug.cgi?id=106669.

Original patch by Sebastian Dröge.
Reviewed by Csaba Osztrogonác.

Source/WebCore:

* WebCore.pri:

Tools:

Build with GStreamer 1.0 if available, but support GStreamer 0.10
temporarily to make upgrading easy and the patch suitable for Qt5.

* qmake/mkspecs/features/features.prf:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@144208 268f45cc-cd09-0410-ab3c-d52691b4dbfc