core/mount: filter out noauto,auto,nofail,fail options

core/mount: filter out noauto,auto,nofail,fail options

We passed the full option string from fstab to /bin/mount. It would in
turn pass the full option string to its helper, if it needed to invoke
one. Some helpers would ignore things like "nofail", but others would
be confused. We could try to get all helpers to ignore those
"meta-options", but it seems better to simply filter them out.

In our model, /bin/mount simply has no business in knowing whether the
mount was configured as fail or nofail, auto or noauto, in the
fstab. If systemd tells invokes a command to mount something, and it
fails, it should always return an error. It seems cleaner to filter
out the option, since then there's no doubt how the command should
behave.

https://bugzilla.redhat.com/show_bug.cgi?id=1177823