the old EvaluateAsInt method has been dropped as from current clang

Change-Id: Ie30d1547ad8de777badff4b380d2fc9fb261e8fe
Reviewed-on: https://gerrit.libreoffice.org/64107
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>