i123485 secured file import scanning existing pages
i123485 secured file import scanning existing pages

(cherry picked from commit 04b38114b0ca4be9895d8f9fa842b6cb390c8036
 and adapted to the rewritten scanBuildPageChainCache)

Change-Id: Ib90d0563be5aeb69aa14c28b3304e42f3cc46162
Reviewed-on: https://gerrit.libreoffice.org/6272
Reviewed-by: Michael Meeks <7e3f212bc57cabc465c9df7f45a34ee84553965e@collabora.com>
Tested-by: Michael Meeks <7e3f212bc57cabc465c9df7f45a34ee84553965e@collabora.com>

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core