Fixed QtMultimedia core namespace compilation.

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

src/plugins/gstreamer/mediacapture/qgstreamerimageencode.h

@@ -42,15 +42,16 @@
 #ifndef QGSTREAMERIMAGEENCODE_H
 #define QGSTREAMERIMAGEENCODE_H
 
-class QGstreamerCaptureSession;
-
 #include <qimageencodercontrol.h>
 
 #include <QtCore/qstringlist.h>
 #include <QtCore/qmap.h>
 
 #include <gst/gst.h>
-QT_USE_NAMESPACE
+
+QT_BEGIN_NAMESPACE
+
+class QGstreamerCaptureSession;
 
 class QGstreamerImageEncode : public QImageEncoderControl
 {
@@ -77,4 +78,6 @@ private:
     QGstreamerCaptureSession *m_session;
 };
 
+QT_END_NAMESPACE
+
 #endif