Fix resource leak closing SDL RW ops

Leak introduced in b3d134a6b7 ("merged
physfs branch"), but this fix only applies after the conversion to RAII.
An equivalent change from SDL_FreeRW->SDL_RWclose is needed for pre-RAII
code.

Fixes: d0de0cf963 ("Use unique_ptr for SDL_RWops")

common/arch/sdl/digi_mixer_music.cpp

@@ -31,7 +31,10 @@ class current_music_t
 {
 	struct RWops_delete
 	{
-		void operator()(SDL_RWops *o) { SDL_FreeRW(o); }
+		void operator()(SDL_RWops *o)
+		{
+			SDL_RWclose(o);
+		}
 	};
 	struct Music_delete
 	{

d2x-rebirth/include/physfsrwops.h

@@ -42,7 +42,7 @@ struct RWops_delete
 {
 	void operator()(SDL_RWops *o) const
 	{
-		SDL_FreeRW(o);
+		SDL_RWclose(o);
 	}
 };