Fix 'iptables -p !' bug (segfault when `!' used without argument)
diff --git a/extensions/libipt_SNAT.c b/extensions/libipt_SNAT.c
index 1af0d5e..9493a14 100644
--- a/extensions/libipt_SNAT.c
+++ b/extensions/libipt_SNAT.c
@@ -153,7 +153,7 @@
 
 	switch (c) {
 	case '1':
-		if (check_inverse(optarg, &invert))
+		if (check_inverse(optarg, &invert, NULL, 0))
 			exit_error(PARAMETER_PROBLEM,
 				   "Unexpected `!' after --to-source");