Wayland: Check custom cursor resource reference for cache invalidation

Images don't have RIDs and this way of checking stuff broke the cursor
cache. Let's do like all other platforms and check the resource
reference instead.

platform/linuxbsd/wayland/display_server_wayland.cpp

@@ -1033,7 +1033,7 @@ void DisplayServerWayland::cursor_set_custom_image(const Ref<Resource> &p_cursor
 		HashMap<CursorShape, CustomCursor>::Iterator cursor_c = custom_cursors.find(p_shape);
 
 		if (cursor_c) {
-			if (cursor_c->value.rid == p_cursor->get_rid() && cursor_c->value.hotspot == p_hotspot) {
+			if (cursor_c->value.resource == p_cursor && cursor_c->value.hotspot == p_hotspot) {
 				// We have a cached cursor. Nice.
 				wayland_thread.cursor_set_shape(p_shape);
 				return;
@@ -1049,7 +1049,7 @@ void DisplayServerWayland::cursor_set_custom_image(const Ref<Resource> &p_cursor
 
 		CustomCursor &cursor = custom_cursors[p_shape];
 
-		cursor.rid = p_cursor->get_rid();
+		cursor.resource = p_cursor;
 		cursor.hotspot = p_hotspot;
 
 		wayland_thread.cursor_shape_set_custom_image(p_shape, image, p_hotspot);

platform/linuxbsd/wayland/display_server_wayland.h

@@ -101,7 +101,7 @@ class DisplayServerWayland : public DisplayServer {
 	};
 
 	struct CustomCursor {
-		RID rid;
+		Ref<Resource> resource;
 		Point2i hotspot;
 	};