netfilter: ipset: hash:ip,port,net set type support

The module implements the hash:ip,port,net type support in four flavours:
for IPv4 and IPv6, both without and with timeout support. The elements
are three dimensional: IPv4/IPv6 address, protocol/port and IPv4/IPv6
network address/prefix triples. The different prefixes are searched/matched
from the longest prefix to the shortes one (most specific to least).
In other words the processing time linearly grows with the number of
different prefixes in the set.

Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>