c76da1f010
Make freebsd-update(8) support jails by adding the -j flag which takes a jail jid or name as an argument. This takes advantage of the recently added -j support to freebsd-version(8) in order to get the version of the installed userland. Reviewed by: dteske, kevans MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D25711