fixes pr #3998; diff from frank denis, though slightly different fix
committed;
help and ok millert@

fallout from the deferred dns lookups
noticed by dhartmei@

via mixerctl.conf.
ok deraadt@, earlier version ok henning@

ntp_settime() -> priv_settime()
ntp_host_dns() -> priv_host_dns()

From: Joerg Sonnenberger <joerg@britannica.bec.de>

ok henning@

from otto and myself; prodded by henning;

ok otto@

easier on portable.  ok henning@

anymore, same thing for us and it makes darren's life easier for the
portable

Noticed by mepch@.  OK pedro@ and deraadt@

to an interface; no change in default config
from Toni Mueller <support@oeko.net>, ja ja ja ja bob

ok krw@ millert@

ok markus@ krw@ cloder@ millert@

ok djm@

precision field when we reply in server mode accordingly. from phessler

IBM/Digital API.

plus one

by form@pdp-11.org.ru.
ok todd@ henning@

changes in NetBSD by Christos.  OK otto@

ok drahn@, millert@

inherit rootdelay from the delay from the last client update from the peer
that we picked last time to adjust the local clock.
in some cases we use the average offset between two peers' client updates,
then use the average delay between the two as well.

and such

code path for NTP4 remains unchanged, we already set refid correctly there.
NTP3 and older uses an IPv4 address as refid.
use the IP of the server we last synced to if it was a IPv4 one.
sometimes we use the average offset between two, in that case just pick
one for the IP.
this scheme naturally fails when we query IPv6 servers and have to reply
to IPv4 NTP3 (or even older NTP versions) clients - refid stays at 0 then.
this is a protocol limitation, nothing we can do about it.

might have become invalid (because the peer showed up, dns request sent to
parent, peer vanishes, and then the reply comes back), so do not fatal() in
that case but just log_warnx(). provoked by brad

ok miod@

connect it, instead leave it at -1.
in client_query, set up and connect the socket if it is -1.
and, the real reason for this change: handle connect failures gracefully
ok otto

offset to correct the local clock, but use the median.
given a reasonable sized set of servers this makes us nearly immune against
outliers or flasetickers, without the need for a horribly complicated outliers
detection which does not yield to better results anyway.
test & ok otto