This allows pkg(7) to be used to bootstrap a chroot or jail, and to
recognize the -r and -j arguments and pass them through to pkg(8) if
already bootstrapped.

Note that this does not address the issue of repository keys. If using
a signed package repository, you will still need to copy /usr/share/keys
into the target environment before or after bootstrapping, or pkg will
be unable to verify package signatures.

MFC after: 1 week