it if flags were explicitly specified on the command line. Do not warn
if we were merely trying to preserve flags or remove UF_NODUMP. NFS does
not support flags.
I'm not sure that this is ideal, but it should do for now. Installing
a plain file onto a NFS server must work, we used to silently ignore the
attempt. Doing a binary install looses the flags anyway since cpio
doens't preserve them with the cdrom/network images.
XXX make world should not use flags or chown/chgrp in the obj/tmp area.
This is based on a suggestion from Ken Merry <ken@plutotech.com>.