fix gcc warnings

Max Kellermann <max@duempel.org>
diff --git a/extensions/libxt_CONNSECMARK.c b/extensions/libxt_CONNSECMARK.c
index a7d7cf7..e8d0a5e 100644
--- a/extensions/libxt_CONNSECMARK.c
+++ b/extensions/libxt_CONNSECMARK.c
@@ -27,7 +27,7 @@
 static const struct option CONNSECMARK_opts[] = {
 	{ "save", 0, 0, '1' },
 	{ "restore", 0, 0, '2' },
-	{ 0 }
+	{ .name = NULL }
 };
 
 static int