As noted in PR#8179 and #8305, there's 64bit alignment issue in
	routing socket.  This has been invisible until IPv6 merge because
	all sockaddr_* structure are sized as multiple of 8 bytes.
	sockaddr_in6 comes as exception and raises alignment issue.

	From what I've looked, many of exisitng programs do like:
		rtm = (struct rt_msghdr *)next;
		sin = (struct sockaddr_in6 *)(rtm + 1);
		sdl = (struct sockaddr_dl *)(sin + 1);
	while sys/net/rtsock.c uses ALIGN().  I feel that sys/net/rtsock.c
	should avoid use of ALIGN() for compatibility with existing codebase,
	but I'm not 100% sure.
	Is there any standard document on this?  If not, I'll change
	sys/net/rtsock.c to generate packed structures (not ALIGN'ed) on
	routing socket reads.

itojun