Add empty AtracCtx2 implementation, and a dev setting to select it. Savestates don't work.

Core/Config.cpp

@@ -699,6 +699,7 @@ static const ConfigSetting soundSettings[] = {
 	ConfigSetting("AchievementSoundVolume", &g_Config.iAchievementSoundVolume, 6, CfgFlag::PER_GAME),
 	ConfigSetting("AudioDevice", &g_Config.sAudioDevice, "", CfgFlag::DEFAULT),
 	ConfigSetting("AutoAudioDevice", &g_Config.bAutoAudioDevice, true, CfgFlag::DEFAULT),
+	ConfigSetting("UseNewAtrac", &g_Config.bUseNewAtrac, false, CfgFlag::DEFAULT),
 };
 
 static bool DefaultShowTouchControls() {