mediawiki: the assigned value is never used

Change-Id: Icb2c4477b96c6bab9004b9c7ead2272b86e78dfb
Reviewed-on: https://gerrit.libreoffice.org/11297
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>