RFR: 8359110: Log accumulated GC and process CPU time upon VM exit [v21]

[Jonas Norlinder]

> Add support to log CPU cost for GC during VM exit with `-Xlog:gc+cpu`.
> 
> 
> [2,430s][info][gc,cpu] GC CPU usage: 22,87% (Process: 26,8926s GC: 6,1491s)

Jonas Norlinder has updated the pull request incrementally with one additional commit since the last revision:

  Align string_dedup_cpu_time error handling to cpu_time/_vmthread_cpu_time's specification

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Changes:
  - all: https://git.openjdk.org/jdk/pull/25779/files
  - new: https://git.openjdk.org/jdk/pull/25779/files/a6564c70..54ac0884

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25779&range=20
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25779&range=19-20

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/25779.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25779/head:pull/25779

PR: https://git.openjdk.org/jdk/pull/25779