This adds CONFIG_IP_NF_SET, which provides a match which lets you use
IP sets; the match depends on whether a checked source or destination 
address/network address/port has its bit set in/added to the given set.
It also provides a SET target, which can be used to add or remove the 
addresses/ports of a packet to/from a set. The currently supported types 
of the sets are: ipmap, macipmap, portmap, iphash, nethash and iptree. 
It is possible to chain sets together by binding.

The userspace program ipset(8) is required to define and setup IP sets.
