RFR: 8315149: Add hsperf counters for CPU time of internal GC threads [v41]

[Jonathan Joo]

On Sat, 11 Nov 2023 00:23:28 GMT, Jonathan Joo <jjoo at openjdk.org> wrote:

>> 8315149: Add hsperf counters for CPU time of internal GC threads
>
> Jonathan Joo has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Refactor ConcurrentRefine logic
>  - Make CPUTimeCounters a singleton class

I believe all comments have been addressed and this PR is once again RFR!

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

PR Comment: https://git.openjdk.org/jdk/pull/15082#issuecomment-1811353654