RFR: 8315149: Add hsperf counters for CPU time of internal GC threads [v35]

[Man Cao]

On Tue, 31 Oct 2023 04:23:13 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 one additional commit since the last revision:
> 
>   Replace NULL with nullptr

LGTM still, thanks!

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Marked as reviewed by manc (Committer).

PR Review: https://git.openjdk.org/jdk/pull/15082#pullrequestreview-1707049281