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: r240336:
Simply things so that "#REQUIRE: FILESYSTEMS" means the file
systems are fully "ready to go".

'FILESYSTEMS' states: "This is a dummy dependency, for services which
require file systems to be mounted before starting." However, we have
'var' which is was run after 'FILESYSTEMS' and can mount /var if it
already isn't mounted. Furthermore, several scripts cannot use /var
until 'cleanvar' has done its thing. Thus "FILESYSTEMS" hasn't really
meant all critical file systems are fully usable.

MFC r231563: start watchdogd before most of other daemons/servers

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

"REQUIRE: cleanvar" for all RC's writing into /var/run.

Remove the requirement for the FreeBSD keyword as it no longer
makes any sense.

Discussed with: dougb, brooks
MFC after: 3 days

Removes the check for the existence of the sysctl variable
debug.watchdog since it is not created by hardware watchdog(4) devices.
The watchdog(4) device is always compiled in the kernel, so removing the
check should not cause any problems.

Approved by: phk

Mark scripts as not usable inside a jail by adding keyword 'nojail'.

Some suggestions from: rwatson, Ruben de Groot <mail25@bzerk.org>

- Add a software watchdog facility.

This commit has two pieces. One half is the watchdog kernel code which lives
primarily in hardclock() in sys/kern/kern_clock.c. The other half is a userland
daemon which, when run, will keep the watchdog from firing while the userland
is intact and functioning.

Approved by: jeff (mentor)