region: Change resource to a wl_resource pointer

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
diff --git a/src/compositor.h b/src/compositor.h
index 865b01c..a56bd4d 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -571,7 +571,7 @@
 };
 
 struct weston_region {
-	struct wl_resource resource;
+	struct wl_resource *resource;
 	pixman_region32_t region;
 };