For JDK-8301403 we needed to change a few defines in src/hotspot/share/utilities/globalDefinitions.hpp from "const" to "constexpr", but now we are left with mixture of both.

I think we should change the remaining definitions from const to constexpr to be consistent.

constexpr is semantically identical to const, with the added benefit of being computed at compile-time, and can be used to define array's sizes, where const can not.