mount.nfs: don't overwrite mount options from /etc/nfsmount.conf

mount.nfs: don't overwrite mount options from /etc/nfsmount.conf

The libmount (as well as mount(8)) ignores mount options from command
line if running in restricted mode (suid, non-root-user) and all
options are read from fstab only.

It means that all options are replaced with stuff from fstab,
including mount options from nfsmount.conf. This is bug.

We have to apply fstab and then nfsmount.conf.

Signed-off-by: Karel Zak <kzak@redhat.com>
Signed-off-by: Steve Dickson <steved@redhat.com>