[NETFILTER]: Add iptables CLUSTERIP target, seq_file version

[NETFILTER]: Add iptables CLUSTERIP target, seq_file version

This enables you to build a static load sharing cluster between multiple
nodes - without the requirement to have a load balancer.  It uses a
series of [evil] tricks like replying with linklayer multicast addresses
to ARP requests, and using CONNMARK for stateful blocking all traffic
not intended for the local node.

Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>