Fixing building on Windows if SDL_Mixer is not a target

CHANGELOG.txt

@@ -6,6 +6,7 @@ main/kconfig.c: Fixing issue when assigning mouse button if a citem is still poi
 arch/sdl/digi_mixer_music.c: Fixing issue introduced in rev1139: Game could of course not open music files which are not inside Searchpath or added to it - re-added playing over absolute path
 main/net_ipx.c, main/net_udp.c: When selecting coop game mode, make sure that besides max players menu values also actual player number is set and menu text is updated properly
 main/net_udp.h: Reducing sending objects per frame from 20 to 1 again to reduce possibility of timeout on stressed systems
+main/songs.c: Fixing building on Windows if SDL_Mixer is not a target
 
 20100704
 --------

main/songs.c

@@ -420,8 +420,10 @@ int songs_play_level_song( int levelnum, int offset )
 						Song_playing = songnum;
 					}
 				}
+#ifdef USE_SDLMIXER
 				else
 #endif
+#endif
 #ifdef USE_SDLMIXER
 				{
 					if (mix_play_file(Songs[songnum].filename, 1, NULL))