These were left over from $FreeBSD$ removal.
Reviewed by: emaste
Differential Revision: https://reviews.freebsd.org/D42612
(cherry picked from commit 1ca63a8219b88b752b064d19bd3428c61dbcf1f9)
This does not include the new hash routines since they will cause problems
when reading old hash files.
Since mpool(3) has been changed, provide a compatibility shim for older
binaries.
Obtained from: OpenBSD