Fixed QtMultimedia core namespace compilation.

Change-Id: Ie276a7766bd26f3e49b2bc9c1a28ec96f1e3e4b0
Reviewed-by: Michael Goddard <michael.goddard@nokia.com>

src/multimedia/gsttools_headers/qgstutils_p.h

@@ -56,6 +56,8 @@
 #include <QtCore/qmap.h>
 #include <gst/gst.h>
 
+QT_BEGIN_NAMESPACE
+
 class QSize;
 class QVariant;
 class QByteArray;
@@ -67,4 +69,6 @@ namespace QGstUtils {
     QSize capsCorrectedResolution(const GstCaps *caps);
 }
 
+QT_END_NAMESPACE
+
 #endif