Bring in FreeBSD/1.218.

Bring in FreeBSD/1.218.
>date: 2004/05/11 19:14:44;  author: maxim;  state: Exp;  lines: +1 -1
>o Calculate a number of bytes to copy (cnt) correctly:
>
>  +----+-+-+-+-+----+----+- - - - - - - - - - - -  -+----+
>  |    | |C| | |    |    |                          |    |
>  | IP |N|O|L|P|    | IP |                          | IP |
>  | #1 |O|D|E|T|    | #2 |                          | #n |
>  |    |P|E|N|R|    |    |                          |    |
>  +----+-+-+-+-+----+----+- - - - - - - - - - - -  -+----+
>               ^    ^<---- cnt - (IPOPT_MINOFF - 1) ---->|
>               |    |
>src            |    +-- cp[IPOPT_OFF + 1] + sizeof(struct in_addr)
>               |
>dst            +-- cp[IPOPT_OFF + 1]
>
>PR:             kern/66386
>Submitted by:   Andrei Iltchenko