Add ntpdate_hosts to rc.conf

[John Marshall]

Request:	Please add "ntpdate_hosts" to /etc/defaults/rc.conf

Context:	FreeBSD 5.4-RELEASE-p7 i386

Reasons:	- The /etc/rc.d/ntpdate script looks for it
		- It's missing from rc.conf
		- It's not documented
		- Adding the hosts to the existing "ntpdate_flags"
variable
		  produces unexpected results.

Background:
To the uninitiated, the only apparent "standard" tweaking mechanisms for
any startup script appear to be those included in rc.conf. For ntpdate,
the only tweaks presented in the defaults file are:
	- ntpdate_enable
	- ntpdate_program
	- ntpdate_flags

If the list of hosts is appended to ntpdate_flags (where else would it
go?), then the ntpdate startup script uses them but also appends any
hosts listed as servers in /etc/ntp.conf. The script does this because
it didn't find any hosts via ntpdate_hosts, it doesn't know that you
supplied the hosts via the ntpdate_flags mechanism, it knows that
there's no point running without pointing at any hosts, so it goes and
finds some from ntp.conf. In a scenario where the ntp.conf hosts are not
accessible until after the system startup has finished, this will stall
the startup.

If an empty ntpdate_hosts is added to rc.conf, then people will know
which mechanism to use. An empty ntpdate_hosts list variable will still
result in the ntpdate script looking in ntp.conf, so no harm done there.
A populated ntpdate_hosts list variable keeps the startup script away
from ntp.conf and uses only the listed hosts.

Something like the following in /etc/defaults/rc.conf would make this a
whole lot more intuitive.

	ntpdate_hosts=""		# (use hosts from /etc/ntp.conf
if blank)

Thank you for listening.

John Marshall
Sydney, NSW, Australia