desktop-shell: Remove output_move listener on shutdown

https://bugs.freedesktop.org/show_bug.cgi?id=78138
diff --git a/desktop-shell/shell.c b/desktop-shell/shell.c
index 8b67844..bbc61cf 100644
--- a/desktop-shell/shell.c
+++ b/desktop-shell/shell.c
@@ -5976,6 +5976,7 @@
 	}
 
 	wl_list_remove(&shell->output_create_listener.link);
+	wl_list_remove(&shell->output_move_listener.link);
 
 	wl_array_for_each(ws, &shell->workspaces.array)
 		workspace_destroy(*ws);