Remove an unneeded include.

src/game_events.cpp

@@ -40,6 +40,7 @@
 #include "resources.hpp"
 #include "scripting/lua.hpp"
 #include "sound.hpp"
+#include "soundsource.hpp"
 #include "terrain_filter.hpp"
 #include "unit_display.hpp"
 #include "wml_exception.hpp"

src/game_events.hpp

@@ -19,7 +19,6 @@
 #include "map.hpp"
 #include "map_location.hpp"
 #include "serialization/string_utils.hpp"
-#include "soundsource.hpp"
 #include "variable.hpp"
 #include "unit_map.hpp"
 

src/savegame_config.cpp

@@ -12,6 +12,7 @@
 */
 
 #include "sound.hpp"
+#include "soundsource.hpp"
 #include "game_events.hpp"
 
 namespace savegame {