Fix logic checking the ignore_lostfound argument.

 * Check with:

    $ unset ilost;    test -n "$ilost" -a "$ilost" != 0 && echo "setting ignore_lostfound="

    $ ilost=0;        test -n "$ilost" -a "$ilost" != 0 && echo "setting ignore_lostfound="

    $ ilost=1;        test -n "$ilost" -a "$ilost" != 0 && echo "setting ignore_lostfound="
      setting ignore_lostfound=