instead of mixing and matching rtl::Reference and tools::SvRef, lets
just use rtl::Reference

Change-Id: I5d77c8a662e1455f97935e5f4a99e484e8cad332
Reviewed-on: https://gerrit.libreoffice.org/43205Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
Tested-by: Noel Grandin <noel.grandin@collabora.co.uk>