Remove faith(4) and faithd(8) from the tree.

Remove faith(4) and faithd(8) from the tree.

FreeBSD did that 3 years ago (r274331). Quoting from their commit msg:

-----8<-----
It looks like industry have chosen different (and more traditional)
stateless/stateful NAT64 as translation mechanism. Last non-trivial
commits to both faith(4) and faithd(8) happened more than 12 years
ago, so I assume it is time to drop RFC3142 in FreeBSD.
----->8-----

Some more info here:

https://lists.freebsd.org/pipermail/freebsd-net/2014-October/040224.html

Discussed-with: sephe