wined3d: Avoid calling wined3d_surface_set_mem() in surface_cleanup().

Calling wined3d_surface_set_mem() might cause the surface container to be
accessed, for example when invalidating resource locations. This would become
a problem once we assume surfaces always have a container, and is pointless
anyway because the surface is being destroyed.

dlls/wined3d/surface.c

@@ -96,7 +96,8 @@ static void surface_cleanup(struct wined3d_surface *surface)
     }
 
     if (surface->flags & SFLAG_USERPTR)
-        wined3d_surface_set_mem(surface, NULL, 0);
+        surface->resource.allocatedMemory = NULL;
+
     if (surface->overlay_dest)
         list_remove(&surface->overlay_entry);