AF_LINK may not be the first address returned for the interface.
Technically, it *might* not even exist on the interface even though
other families do.
This is likely a driver bug if this really is the case though.
As such it's just easier to use direct ioctls rather than thump around
getifaddrs results. As it stands, the code makes a lot of getifaddrs
calls anyway, so an extra ioctl or two won't break the bank.