Bugfix: Returning to the menus from a race does not return the theme

music.  


git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/trunk/supertuxkart@1471 178a84e3-b1eb-0310-8ba1-8eac791a3b58

src/game_manager.cpp

@@ -87,6 +87,7 @@ void GameManager::run()
 
         if (race_manager->raceIsActive())
         {
+            music_on = false; 
             scene->draw((m_curr_time - m_prev_time ) * 0.001f);
             if ( world->getPhase() != World::LIMBO_PHASE)
             {