RFR: 8369569: Rename methods in regmask.hpp to conform with HotSpot coding style [v2]

[Daniel Lundén]

> A number of methods in regmask.hpp do not conform with the HotSpot coding style. We should make sure they do.
> 
> ### Changeset
> - Rename methods in `regmask.hpp` to conform with HotSpot coding style.
> - Similarly rename directly related methods in `chaitin.hpp`.
> - Rename the constant register masks `All` and `Empty` to `ALL` and `EMPTY`.
> - Fix a few additional code style issues at lines touched by the changeset.
> 
> Note: this is a syntax-only changeset (no functional changes).
> 
> ### Testing
> 
> - [GitHub Actions](https://github.com/dlunde/jdk/actions/runs/18500704336)
> - `tier1` and HotSpot parts of `tier2` and `tier3` (and additional Oracle-internal testing) on Windows x64, Linux x64, Linux aarch64, macOS x64, and macOS aarch64.

Daniel Lundén has updated the pull request incrementally with one additional commit since the last revision:

  Apply suggestions from code review
  
  Co-authored-by: Roberto Castañeda Lozano <robcasloz at users.noreply.github.com>

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/27817/files
  - new: https://git.openjdk.org/jdk/pull/27817/files/1a9c93a9..b44a9a6f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27817&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27817&range=00-01

  Stats: 5 lines in 1 file changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/27817.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27817/head:pull/27817

PR: https://git.openjdk.org/jdk/pull/27817