We don't implement dfdl:occursCountKind="stopValue", so the presence of occursStopValue="-1" in our schemas is unnecessary.
The current version of IBM DFDL we are cross testing against for portability doesn't tolerate this, so we should just remove it everywhere. IBM has a bug ticket about this. This should let tests for schemas AF.dfdl.xsd, AX.dfdl.xsd, AY.dfdl.xsd, AZ.dfdl.xsd, etc. all work portably now.