Don't attempt to configure Legacy IP address on tun device.

Don't attempt to configure Legacy IP address on tun device.

This was only setting the Legacy IP address and not IPv6, and it wasn't
setting up any routes or nameservers. It wasn't even setting a *netmask*,
so wasn't even useful in the simple case of a VPN serving a single network
range. I can't think of a single case in which it was actually useful.

This is my response to the patch from Stanislav Sedov which makes the IP
configuration code work on FreeBSD 10. The tun code is a big enough mess
of OS-specific ifdefs already; I don't want it getting even worse, so let's
just rip this bit out.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>