Fixes CVE-2019-7310.

Add patch to fix CVE-2019-9200 too.

CVE-2018-20662 looks irrelevant because we don't build pdfunite tool.

Change-Id: I5e7ddabbb341f6bfefb376d552b50c4006f41906
Reviewed-on: https://gerrit.libreoffice.org/69094
Tested-by: Jenkins
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>