Make the FAT setattr handling more consistent about unsupported attributes;  making it more "user-friendly".  Mostly from FreeBSD. OK guenther@, krw@.
Make the FAT setattr handling more consistent about unsupported
attributes;  making it more "user-friendly".  Mostly from FreeBSD.
OK guenther@, krw@.

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars