Lower the length that we allow the checkout directory to be,
to avoid errors during nullfs and linprocfs mounts
during the build.  poudriere uses a lot of mounts when building ports,
and if the checkout directory is too long, during nullfs
and linprocfs mounts, we will overshoot MNAMELEN, which is a hardcoded
value in the FreeBSD kernel mount code.  This will cause
mounts to fail.

Ticket: #5463
Document reboot and shutdown resources

Ticket:	#5477