Pull up following revision(s) (requested by martin in ticket #754):
usr.sbin/sysinst/menus.mi: revision 1.6
usr.sbin/sysinst/msg.mi.de: revision 1.5
usr.sbin/sysinst/msg.mi.en: revision 1.5
usr.sbin/sysinst/msg.mi.es: revision 1.5
usr.sbin/sysinst/msg.mi.fr: revision 1.5
usr.sbin/sysinst/msg.mi.pl: revision 1.5
Change the IPv6 DNS selection to use DNS selection and add the
Google Public V4 DNS servers to the list.
The other field can take an IPv4 or IPv6 name server of choice.
Fixes PR install/49231.

(snj)