TrackContainer: fix Qt header includes

Always prefix Qt header includes with name of according module.
(cherry picked from commit bb57d53770)

include/track_container.h

@@ -2,8 +2,8 @@
  * track_container.h - base-class for all track-containers like Song-Editor,
  *                     BB-Editor...
  *
- * Copyright (c) 2004-2008 Tobias Doerffel <tobydox/at/users.sourceforge.net>
- * 
+ * Copyright (c) 2004-2009 Tobias Doerffel <tobydox/at/users.sourceforge.net>
+ *
  * This file is part of Linux MultiMedia Studio - http://lmms.sourceforge.net
  *
  * This program is free software; you can redistribute it and/or
@@ -23,11 +23,10 @@
  *
  */
 
-
 #ifndef _TRACK_CONTAINER_H
 #define _TRACK_CONTAINER_H
 
-#include <QReadWriteLock>
+#include <QtCore/QReadWriteLock>
 
 #include "track.h"
 #include "JournallingObject.h"