Add level_nosync tune, played if GTR_NOPOSITION

- Does not reset if level music does not change between
  levels

src/music.cpp

@@ -35,6 +35,13 @@ void Music_Init(void)
 		tune.nightcoreable = true;
 	}
 
+	{
+		Tune& tune = g_tunes.insert("level_nosync", g_tunes.find("level"));
+
+		tune.sync = false;
+		tune.resist = true;
+	}
+
 	{
 		Tune& tune = g_tunes.insert("position");
 

src/p_setup.c

@@ -8110,11 +8110,27 @@ void P_ResetLevelMusic(void)
 
 void P_LoadLevelMusic(void)
 {
-	tic_t level_music_start = starttime + (TICRATE/2);
+	const char *music = mapheaderinfo[gamemap-1]->musname[mapmusrng];
 
 	Music_StopAll();
-	Music_Remap("level", mapheaderinfo[gamemap-1]->musname[mapmusrng]);
-	Music_Seek("level", max(leveltime, level_music_start) - level_music_start);
+
+	if (gametyperules & GTR_NOPOSITION)
+	{
+		if (stricmp(Music_Song("level_nosync"), music))
+		{
+			Music_Stop("level_nosync"); // reset when music changes
+		}
+		Music_Remap("level_nosync", music);
+	}
+	else
+	{
+		Music_Stop("level_nosync");
+		Music_Remap("level_nosync", ""); // signal that this should not play
+		Music_Remap("level", music);
+
+		tic_t level_music_start = starttime + (TICRATE/2);
+		Music_Seek("level", max(leveltime, level_music_start) - level_music_start);
+	}
 }
 
 /** Loads a level from a lump or external wad.

src/p_tick.c

@@ -975,7 +975,11 @@ void P_Ticker(boolean run)
 			if (leveltime == (starttime + (TICRATE/2)))
 			{
 				// Plays the music after the starting countdown.
-				Music_Play("level");
+				if (!Music_Playing("level_nosync"))
+				{
+					// Do not stop level_nosync
+					Music_Play(Music_Song("level_nosync")[0] ? "level_nosync" : "level");
+				}
 			}
 			else if (starttime != introtime)
 			{