coverity#1038307 Negative loop bound
coverity#1038307 Negative loop bound

Change-Id: Ib0ca4fc350d84e25283e261cb9f48b0f6f22e81b
Reviewed-on: https://gerrit.libreoffice.org/4556
Reviewed-by: Michael Stahl <eef8671db506f9731c0438a7613853b6391ca841@redhat.com>
Tested-by: Michael Stahl <eef8671db506f9731c0438a7613853b6391ca841@redhat.com>

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