Uh, ya, sure this almost compiled for bsdi. NOT!

Note that bsdis_/_i_/_os_/__ has moved this file to dev/ic/ and
has completely removed the non-compiling function from pdq_ifsubr.c and
has completely removed this function and placed it into netinet/if_ether.c
(if, in fact, it wasn't there the whole time). I was tempted to simply
remove this bsdionly__ function.

The function is arp_ifinit().

PR: kern/7903