Revert djgppdos fade function inadvertent merge

src/djgppdos/i_sound.c

@@ -566,45 +566,6 @@ boolean I_SetSongTrack(INT32 track)
 	return false;
 }
 
-/// ------------------------
-// MUSIC FADING
-/// ------------------------
-
-void I_SetInternalMusicVolume(UINT8 volume)
-{
-	(void)volume;
-}
-
-void I_StopFadingSong(void)
-{
-}
-
-boolean I_FadeSongFromVolume(UINT8 target_volume, UINT8 source_volume, UINT32 ms, void (*callback)(void));
-{
-	(void)target_volume;
-	(void)source_volume;
-	(void)ms;
-	return false;
-}
-
-boolean I_FadeSong(UINT8 target_volume, UINT32 ms, void (*callback)(void));
-{
-	(void)target_volume;
-	(void)ms;
-	return false;
-}
-
-boolean I_FadeOutStopSong(UINT32 ms)
-{
-	(void)ms;
-	return false;
-}
-
-boolean I_FadeInPlaySong(UINT32 ms, boolean looping)
-{
-        (void)ms;
-        (void)looping;
-        return false;
 // Is the song playing?
 #if 0
 int I_QrySongPlaying(int handle)