This fixes some minor CVEs.

Not including the fix for CVE-2018-18064, which does not affect LO
because we use the default implementation of FT_Memory which uses
free/malloc.

Change-Id: Ic047ed52cff3fdeba068f1b8d303c6c96c69addd
Reviewed-on: https://gerrit.libreoffice.org/68088
Tested-by: Jenkins
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>