xdg-shell: fix invalid wlr_xdg_positioner alloc

types/wlr_xdg_shell.c

@@ -399,7 +399,7 @@ static const struct xdg_positioner_interface
 static void xdg_shell_handle_create_positioner(struct wl_client *wl_client,
 		struct wl_resource *resource, uint32_t id) {
 	struct wlr_xdg_positioner *positioner =
-		calloc(1, sizeof(struct wlr_xdg_positioner_resource));
+		calloc(1, sizeof(struct wlr_xdg_positioner));
 	if (positioner == NULL) {
 		wl_client_post_no_memory(wl_client);
 		return;