fixed broken clearAllTracks()

git-svn-id: https://lmms.svn.sf.net/svnroot/lmms/trunk/lmms@1174 0778d3d1-df1d-0410-868b-ea421aaaa00d

src/core/track_container.cpp

@@ -172,12 +172,10 @@ void trackContainer::updateAfterTrackAdd( void )
 
 void trackContainer::clearAllTracks( void )
 {
-	for( trackList::iterator it = m_tracks.begin();
-						it != m_tracks.end(); ++it )
+	while( !m_tracks.isEmpty() )
 	{
-		delete *it;
+		delete m_tracks.first();
 	}
-	m_tracks.clear();
 }