This adds CONFIG_IP_NF_SET, which provides a match which lets you use
IP address/network address/port sets; the match depends on whether a 
checked source or destination address/network address/port has its bit 
set in/added to the 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
and iphash. It is possible to define multilevel sets up to a hardcoded
level.

The userspace program ipset(8) is also compiled (in the ipset/
directory), and is used to define the sets and their bounds.
