Pull up following revision(s) (requested by ozaki-r in ticket #701):
sys/netinet/in.c: 1.227
sys/netinet6/in6.c: 1.265
tests/net/arp/t_arp.sh: 1.35-1.36
Make GARP work again when DAD is disabled
The change avoids setting an IP address tentative on initializing it when
the IPv4 DAD is disabled (net.inet.ip.dad_count=0), which allows a GARP packet
to be sent (see arpannounce).  This is the same behavior of NetBSD 7, i.e.,
before introducing the IPv4 DAD.
Additionally do the same change to IPv6 DAD for consistency.
The change is suggested by roy@
--
Improve packet checks and error reporting
--
Add tests for GARP without DAD
Additionally make the existing tests for GARP more explicit.

(snj)