shell,compositor-x11: Fix trivial memory leaks

Signed-off-by: Ryo Munakata <ryomnktml@gmail.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/src/compositor-x11.c b/src/compositor-x11.c
index aa1e519..e9735c5 100644
--- a/src/compositor-x11.c
+++ b/src/compositor-x11.c
@@ -1454,6 +1454,8 @@
 		if (atom[i] == c->atom.net_wm_state_fullscreen)
 			c->has_net_wm_state_fullscreen = 1;
 	}
+
+	free(reply);
 }
 
 static void