Fix sparse warnings: non-ANSI function declarations, 0 used as pointer
diff --git a/extensions/libip6t_icmp6.c b/extensions/libip6t_icmp6.c
index 5c06c04..0210849 100644
--- a/extensions/libip6t_icmp6.c
+++ b/extensions/libip6t_icmp6.c
@@ -53,7 +53,7 @@
 };
 
 static void
-print_icmpv6types()
+print_icmpv6types(void)
 {
 	unsigned int i;
 	printf("Valid ICMPv6 Types:");
@@ -86,8 +86,8 @@
 }
 
 static const struct option opts[] = {
-	{ "icmpv6-type", 1, 0, '1' },
-	{0}
+	{ "icmpv6-type", 1, NULL, '1' },
+	{ }
 };
 
 static void