sorry for the mess.  this is because of a transition from NetBSD-only
	AF_INET6 socket behavior, to more standardized AF_INET6 socket behavior.

	before:
	- on an AF_INET6 socket, normally you can't grab IPv4 traffic.
	  to grab it, you need to setsockopt(IPV6_BINDV6ONLY, 0).
	- on an AF_INET6 socket, you can always connect to IPv4 destination
	  by using IPv4 mapped address (::ffff:10.1.1.1).
	now:
	- on an AF_INET6 socket, normally you can't grab IPv4 traffic.
	  to grab it, you need to setsockopt(IPV6_V6ONLY, 0).
	- on an AF_INET6 socket, you can't connect to IPv4 destination
	  by using IPv4 mapped address.  to do this, you need to
	  setsockopt(IPV6_V6ONLY, 0).

	mozilla uses IPv4 mapped address on AF_INET6 socket, to connect to
	IPv4 destinations on an IPv6-ready kernel.  therefore they no longer
	be able to establish connections to IPv4 destinations.
	taya@netbsd is now working on a workaround, also he is contacting
	mozilla folks to use AF_INET sockets for IPv4 (this is more preferable
	approach than to use IPv4 mapped address).

itojun