Export the NAT definitions to userspace. So far userspace (specifically,
iptables) has been copying the headers files from include/net. Also
rename some structures and definitions in preparation for IPv6 NAT.
Since these have never been officially exported, this doesn't affect
existing userspace code.
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>