Add ntpdate_hosts to rc.conf

[John Marshall]

Alex,

> If you choose to use ntpd, your problem goes away. 

Thank you for your words of wisdom, but I don't have a problem - I
solved one. I didn't post to the list in order to start a discussion
about ntpd or ntpdate.

My only reason for posting was to point out that FreeBSD's ntpdate RC
script uses a variable which is not defined in the default rc.conf (and
doesn't seem to be documented anywhere).

If this is the wrong kind of content for this list - sorry guys.

If nobody's interested in taking up my suggestion of fixing this, that's
fine too. I just thought I'd try and do the right thing.

John.