Revert "Fix #2602: music doesn't change immediately on loading a save"

This reverts commit 94b69e0281.

src/savegame.cpp

@@ -42,7 +42,6 @@
 #include "serialization/binary_or_text.hpp"
 #include "serialization/parser.hpp"
 #include "serialization/utf8_exception.hpp"
-#include "sound.hpp"
 #include "statistics.hpp"
 #include "version.hpp"
 #include "video.hpp"
@@ -205,8 +204,6 @@ bool loadgame::load_game()
 	// read classification to for loading the game_config config object.
 	gamestate_.classification() = game_classification(load_data_.load_config);
 
-	sound::clear_current_track();
-
 	if (skip_version_check) {
 		return true;
 	}

src/sound.cpp

@@ -576,11 +576,6 @@ void empty_playlist()
 	current_track_list.clear();
 }
 
-void clear_current_track()
-{
-	current_track.reset();
-}
-
 void play_music()
 {
 	if(!current_track) {

src/sound.hpp

@@ -53,8 +53,6 @@ void play_music_repeatedly(const std::string& id);
 void play_music_once(const std::string& id);
 // Empty the playlist
 void empty_playlist();
-// Clear current_track, allowing immediate music changes.
-void clear_current_track();
 // Start playing current music.
 void play_music();