Improve video test coverage and debugging output.

Added a few debug operators for some useful enums, and
added tests for them.  One or two other features not really
tested.

Change-Id: Idffec6ade1d4e05dbf72f3dc47dfc0d01ddddf8b
Reviewed-on: http://codereview.qt-project.org/6201
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Jonas Rabbe <jonas.rabbe@nokia.com>

src/multimedia/video/qabstractvideobuffer.h

@@ -102,6 +102,10 @@ private:
     Q_DISABLE_COPY(QAbstractVideoBuffer)
 };
 
+#ifndef QT_NO_DEBUG_STREAM
+Q_MULTIMEDIA_EXPORT QDebug operator<<(QDebug, QAbstractVideoBuffer::HandleType);
+#endif
+
 QT_END_NAMESPACE
 
 Q_DECLARE_METATYPE(QAbstractVideoBuffer::HandleType)