qadevOOo: Convert a primitive type into a string

Change-Id: I1a840346e75a3d7dd0de761660a0ea95c7ee034b
Reviewed-on: https://gerrit.libreoffice.org/11370
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>