When copying their page steam into ours, we need to make sure their
syntax is <= 1.4; so when checking if the image has PDF data, ignore the
case when it has, but it's >= 1.5 (at least in the default case when not
using reference XObjects).

Change-Id: I6bd77803b92fe16bdd327e5e7c3d2b42adeacca4
Reviewed-on: https://gerrit.libreoffice.org/36161Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>