fix OOXML validation error, related fdo#40746

e.g. fdo40746-2.ods exported to OOXML

Change-Id: I48bc7a7d21ddc00eceaeb09970a2b1a60330fbf0
fix another validation error for OOXML, related fdo#40746

e.g. exporting fdo40746-2.ods as OOXML

Change-Id: I8a19ec2caecbc3687229d820ac2ec11fc01facd1