remove GENERIC.v6 file (as it is part of GENERIC now).
"faith" interface is commented out by default as it is not really for
general use.
IPsec items are commented out as well, though we can enable "options IPSEC"
without export-related issue ("options IPSEC" will enable authentication
portion only). We may need to think about it again.
if you have problem compiling with INET6 on archs I do not have access to,
please contact me.
XXX what to do with arch/arm32/SHARK{,.v6}?