compositor: Initialize destroy_listener_list for internal surfaces too

We use this to look up user data on the surface, so make sure the list is
always valid.
diff --git a/src/compositor.c b/src/compositor.c
index 80ee2ba..ef1c6ae 100644
--- a/src/compositor.c
+++ b/src/compositor.c
@@ -199,6 +199,8 @@
 	if (surface == NULL)
 		return NULL;
 
+	wl_list_init(&surface->surface.resource.destroy_listener_list);
+
 	wl_list_init(&surface->link);
 	wl_list_init(&surface->buffer_link);