part of making ScopedWriteAccess an internal detail of vcl

Change-Id: Ida03bc73fe746cde97f6fcb5cde2f066b63d92e9
Reviewed-on: https://gerrit.libreoffice.org/51216Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
Tested-by: Jenkins <ci@libreoffice.org>