config: set "auto_seen" after processing the auto line.

Otherwise when we process an empty autoline (to be sure to
capture the MDADM_CONF_AUTO environment variable) we can end up
setting everything to 'yes' which over-rides 'no'.

Signed-off-by: NeilBrown <neilb@suse.de>
DDF: allow for possibility that there is no secondary copy of metadata.

If there isn't, we currently write the second copy at some
random location :-)

Reported-and-tested-by:  Francis Moreau <francis.moro@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>