7-STABLE firewall gets flushed for both ipv4 and ipv6

Now that ip6fw is deprecated and ipfw does both v4 and v6 there is a 
problem with setup of a firewall. If, for example, you have

firewall_type="some_file"
ipv6_firewall_type="OPEN"

they both will not be setup. Instead, you will end up with just the 
rules from the one settup (depending on rcorder).

In order to work around the issue, I have merged the firewall rules into 
one file and use

firewall_type="/etc/fw/firewall.rules"
ipv6_firewall_type="/etc/fw/firewall.rules"

I don't know of any other way to do this properly.