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

[Jonas Norlinder]

Add support to log CPU cost for GC during VM exit with `-Xlog:gc`.

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Commit messages:
 - Measure GC vtime on VM exit

Changes: https://git.openjdk.org/jdk/pull/25724/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25724&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8359110
  Stats: 178 lines in 15 files changed: 178 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/25724.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25724/head:pull/25724

PR: https://git.openjdk.org/jdk/pull/25724