RFR: 8367397: Improve naming and terminology in regmask.hpp and regmask.cpp [v4]

[Dean Long]

On Fri, 12 Sep 2025 12:40:29 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> I renamed this entire group of constants to use the same style (uppercase separated by `_`, without leading `_`). It is now `WORD_BIT_MASK`. I think it makes more sense to use the same style across `regmask.hpp`, rather than following styles in other files.
>
> Nice!

I would have been OK with CamelCase, but then I would have wondered why the constant wasn't defined in globalDefinitions.hpp instead :-)

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PR Review Comment: https://git.openjdk.org/jdk/pull/27215#discussion_r2345530581