RFR: 8315149: Add hsperf counters for CPU time of internal GC threads [v34]

[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:

  Implement hsperf counter for G1ServiceThread

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15082/files
  - new: https://git.openjdk.org/jdk/pull/15082/files/2fc508f7..0ef70468

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15082&range=33
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15082&range=32-33

  Stats: 19 lines in 4 files changed: 17 ins; 0 del; 2 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