Fix namespace compilation.

Change-Id: Id8d71a48df20da16647834e8f9732012f26f928f
Reviewed-by: Michael Goddard <michael.goddard@nokia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>

src/gsttools/qgstreamervideowidget.cpp

@@ -54,6 +54,8 @@
 #include <gst/interfaces/xoverlay.h>
 #include <gst/interfaces/propertyprobe.h>
 
+QT_BEGIN_NAMESPACE
+
 class QGstreamerVideoWidget : public QWidget
 {
 public:
@@ -350,3 +352,5 @@ void QGstreamerVideoWidgetControl::setSaturation(int saturation)
         emit saturationChanged(saturation);
     }
 }
+
+QT_END_NAMESPACE