XXX shares database file with IPv4 one (0.0.127.in-addr.arpa)

rcmd(): IPv4 only
rcmd_af(): af independent
ruserok(): af independent
iruserok(): IPv4 only
iruserok_sa(): af independent

Submitted by: kevlo@

calloc(), and realloc().  Idea from NetBSD.

DAD before the actual rtsol(8) run happens later.  and since it will rtsol,
it is going to be up in any case.

XXX both "dhcp" and "rtsol" has keyword *down* at the end.  is it okay?

sleep for net.inet6.ip6.dad_count seconds to ensure that IPv6 DAD is completed.
TODO: rtsold (rc.conf line), manpage

to do this,
1. in sysctl.conf, add these lines:
net.inet6.ip6.forwarding=0
net.inet6.ip6.accept_rtadv=1
2. in hostname.foo, add
rtsol
specifying two or more interfaces with "rtsol" may result in strange
behavior - ipv6 spec does not permit multi-interface node to be autoconfig'ed.

- multiple entries support (read: aliases)
- inet6 support
- support for comments (#)
(look for hostname.if(5) commit for syntax details)

removed functionality:
new code will not return AF_LOCAL addrinfo struct.
added funtionality:
SOCK_RAW is permitted as ai_socktype (no servname allowed).
draft-ietf-ipngwg-scopedaddr-format-00.txt

rcsid police on usr.sbin/rtadvd.
add sample config into etc/rtadvd.conf.
add files into distrib/sets/list.

Fix prototypes, propagate const where applicable.

MUST make lo0 up before any IPv6 operations.
it will be considered a pilot error if you don't.
(I prefer to have lo0 initialized automatically)

includes some works from todd@ and millert@
verified by todd@ and millert@

Redefining it as a typedef is an error, as it prevents overloading
on e.g., int/wchar_t separately.