unwanted side effects: font loading takes way longer due to linear checks and it makes no sense to do that for a bugged font; this can better be doen at the lua end if needed at all (hans)

git-svn-id: https://foundry.supelec.fr/svn/luatex/trunk@4742 0b2b3880-5936-4365-a048-eb17d2e5a6bf
update do_ff_info

git-svn-id: https://foundry.supelec.fr/svn/luatex/trunk@4744 0b2b3880-5936-4365-a048-eb17d2e5a6bf