Account for extra tracks in musicclass::play()

Since each soundtrack is no longer guaranteed to be 16, we'll have to
account for their different lengths when playing music.

desktop_version/src/Music.h

@@ -51,6 +51,8 @@ public:
 	bool usingmmmmmm;
 
 	binaryBlob musicReadBlob;
+	int num_pppppp_tracks;
+	int num_mmmmmm_tracks;
 
 	Uint64 songStart;
 	Uint64 songEnd;