ipfw(4): make O_IPVER/ipversion match IPv4 or IPv6, not just IPv4 by itself

[nc]

Summary

ipfw(4): make O_IPVER/ipversion match IPv4 or IPv6, not just IPv4 by itself.

Submitted by: Neel Chauhan <neel AT neelc DOT org>

Test Plan

Try this rule:

ipfw add 1 deny all from any to any ipversion 4

It should deny IPv4 packets

Or this:

ipfw add 1 deny all from any to any ipversion 6

It should deny IPv6 packets.

[donner]

Good catch.