fix uninitialized variable: this is used by EndGame, which is called at the

start of Reset(), and was normally initialized later in Reset().  I havn't seen
any bugs as a result; this just showed up in valgrind.

stepmania/src/GameState.cpp

@@ -79,6 +79,7 @@ GameState::GameState() :
 	m_pCurGame = NULL;
 	m_iCoins = 0;
 	m_timeGameStarted.SetZero();
+	m_bDemonstrationOrJukebox = false;
 
 	ReloadCharacters();