Pull up following revision(s) (requested by ozaki-r in ticket #358):
usr.sbin/rtadvd/rtadvd.c: revision 1.54-1.58
usr.sbin/rtadvd/config.c: revision 1.37
usr.sbin/rtadvd/if.c: revision 1.25
usr.sbin/rtadvd/dump.c: revision 1.15
usr.sbin/rtadvd/rrenum.c: revision 1.20
usr.sbin/rtadvd/logit.h: revision 1.1
usr.sbin/rtadvd/rtadvd.8: revision 1.26
tests/net/ndp/t_ra.sh: revision 1.30
usr.sbin/rtadvd/timer.c: revision 1.14
tests/net/ndp/t_ra.sh: revision 1.31
usr.sbin/rtadvd/advcap.c: revision 1.17

KNF, fix time printing formats.

Don't start another copy of rtadvd if one is running.

PR/52618: Shinichi Doyashiki: Don't exit if adding interface to multicast
group fails. This happens with empty vlan interfaces
- make syscalls checks against -1
- fix errors to print %s: instead of <%s>
XXX: if_vlan is the only pseudo interface in net/ that returns such an
error..

Kill rtadvd surely even if the tests fail in the middle
It may help PR bin/52701.

Change the meaning of the D flag to print errors to stderr instead of
syslog(3) and exit if poll(2) fails (intended to be used with unit-tests).

Mark expandm as preserving format strings.

Let rtadvd not use syslog for logging
Thanks to christos@ now rtadvd can log via stderr instead of syslog
by -D option.
Address PR bin/52701

(martin)