Otherwise the swap out / swap in creates new copy of the underlying PDF
stream.

Change-Id: I88a16a69143783a998201e183bea1a9553e337bd
Reviewed-on: https://gerrit.libreoffice.org/56266Reviewed-by: Ashod Nakashian <ashnakash@gmail.com>
Tested-by: Ashod Nakashian <ashnakash@gmail.com>
Reviewed-on: https://gerrit.libreoffice.org/69626Reviewed-by: Jan Holesovsky <kendy@collabora.com>
Tested-by: Jan Holesovsky <kendy@collabora.com>