Import dhcp6leased(8)

Import dhcp6leased(8)

dhcp6leased is a daemon to manage IPv6 prefix delegations. It requests
a prefix from an upstream DHCPv6 server and configures downstream
network interfaces. rad(8) can be used to advertise available prefixes
to clients.

It's a transmogrified dhcpleased(8), so it's a bit rough around the
edges. But it can already request and renew prefixes and configure
interfaces. It's time to hack on it in-tree.

OK deraadt