We hit a compilation error in ZGC when we defined a constant NumPartitions. This happened because there is a define name NumPartitions inside shenandoahFreeSet.hpp. I propose that this (and its friends) are hid inside the ShenandoahRegionPartitions class, which is the only user of these defines. An alternative would be to prefix the define with something that is unlikely to clash with other parts of HotSpot.

I'll prepare a PR that fixes that I think is a good fix, but then it will be up to the Shenandoah devs to decide what solution is most appropriate in their code.