Moved general gstreamer helper classes into separate library.

Cleaned up configuration of gstreamer with a separate config
test.

Change-Id: I1ec9ee466233687fbcfdc544a12d9fce578e4379
Reviewed-on: http://codereview.qt-project.org/6459
Sanity-Review: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Michael Goddard <michael.goddard@nokia.com>

src/plugins/gstreamer/qgstreamervideowindow.cpp

@@ -40,7 +40,7 @@
 ****************************************************************************/
 
 #include "qgstreamervideowindow.h"
-#include "qgstutils.h"
+#include <private/qgstutils_p.h>
 
 #include <QtCore/qdebug.h>