and drop unused ERRCODE_AREA_OFA_END constant

Change-Id: Ic34ecda7f842c5db93807b3f21aa1062966ca523
Reviewed-on: https://gerrit.libreoffice.org/39089Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
Tested-by: Noel Grandin <noel.grandin@collabora.co.uk>