landlock: make parameters void in ll_create_full_ruleset

For consistency with the other functions that have no paramters.

This amends commit 13b2c56 ("feature: add Landlock support",
2023-10-24) / PR #6078.

src/firejail/landlock.c

@@ -80,7 +80,7 @@ int ll_is_supported(void) {
 	return ll_abi;
 }
 
-static int ll_create_full_ruleset() {
+static int ll_create_full_ruleset(void) {
 	if (!ll_is_supported())
 		return -1;