and drop unused CURSOR_INVALID constant

Change-Id: I190908a03317f93d247c0a9c806c70bb286b8ecb
Reviewed-on: https://gerrit.libreoffice.org/33964Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
Tested-by: Noel Grandin <noel.grandin@collabora.co.uk>