ip6 with a v4 address should emit a parse error

[takikawa]

Here's an example showing the difference between tcpdump and pflua:

$ pflua-compile 'ip6 net 178.79.151.0'
return function(P,length)
   return false
end

$ tcpdump -d 'ip6 net 178.79.151.0'
tcpdump: 'ip6' modifier applied to ip host