fix gcc warnings

Max Kellermann <max@duempel.org>
diff --git a/extensions/libxt_state.c b/extensions/libxt_state.c
index 82f21cd..68f5280 100644
--- a/extensions/libxt_state.c
+++ b/extensions/libxt_state.c
@@ -25,7 +25,7 @@
 
 static const struct option state_opts[] = {
 	{ "state", 1, NULL, '1' },
-	{ }
+	{ .name = NULL }
 };
 
 static int