Relax the limitation of what is an acceptable unicast IP.

Relax the limitation of what is an acceptable unicast IP.

Remove the IN_BADCLASS() check which filters out the experimental IPv4
address space. Now there are no more experiments in IPv4 and so there
is less reason for these network daemons to deny such an IP.
Everything still disallows multicast IPs (224/4) and loopback (127/8)
a few also disallow 0/8 but this is not consistent.

In any case using 240/4 in production is a really bad idea but it is
not up to this software to prevent you from being a fool.

OK deraadt@ tb@