It is really just an SvStream instance, and the lifetime does
not need reference counting
Change-Id: Idb5ffd96f852aae0dc1a94cddc0a83fbcdf974ff
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/165655
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>