RFR: 8315149: Add hsperf counters for CPU time of internal GC threads [v25]

[Jonathan Joo]

> 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:

  Update logic to use cmpxchg rather than add

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15082/files
  - new: https://git.openjdk.org/jdk/pull/15082/files/3eae6bba..9b5772fb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15082&range=24
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15082&range=23-24

  Stats: 15 lines in 2 files changed: 10 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/15082.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15082/head:pull/15082

PR: https://git.openjdk.org/jdk/pull/15082