[PATCH] IPv6: Allow 6to4 routes with SIT

Ok, I've separated out the SIT fix. A revised anycast fix will follow.

This is against 2.5.75. The patch will allow a host to set up SIT
tunnels using gateway routes to 6to4 addresses. Previously this only
worked with an IPv4-compatible address. Use of the deprecated
IPv4-compatible addresses should not be required.

Thanks,

	MikaL