--with-iptables-dir was added to integrate with a proposed system for letting iptables know how to reload our rules. The idea was that we'd save our rules to a file under /etc/sysconfig/iptable.d and the iptables init script would load the rules from there when it was reloading. The proposed system wasn't accepted so, although there might be some theoretical use for this other than the lokkit support, let's just remove it for now.