I.e., modules that use "require = [options]". Nowadays that should be
written as
{
options = { ... };
config = { ... };
};
Also, use "imports" instead of "require" in places where we actually
import another module.
config.krb5.enable needs to be set as true.
Also use pam_ccreds to cache Kerberos credentials for offline logins.
svn path=/nixos/trunk/; revision=22986
