Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r230099:

Change rcvar= assignments to the literal values set_rcvar
would have returned. This will slightly reduce boot time,
and help in diff reduction to HEAD.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Add the shutdown KEYWORD to those scripts that start persistent services
to allow them to do a "clean" shutdown.

I purposely avoided making changes to network-related stuff since the
system shutting down is pretty conclusive, and there may be complicated
dependencies on the network that I would rather not try to unravel.

I also skipped kerberos-related stuff for the reasons above, and
because I have no way to test it.

As previously discussed, add the svn:executable property to all scripts

Add bthidd(8) rc(8) script

MFC after: 1 month