This diff aims to add a jailname and jid builtin variables to support a stable API to get access to jail details. It also allows predicates on jails and therefore filtering traces on a per-jail basis.
zonename was also now added to FreeBSD and it simply falls through to jailname as a compatibility mechanism. The version for the variables is 1.13, as suggested by markj@.
Sponsored by: DARPA, AFRL