RFR: Merge jdk20

[Jesper Wilhelmsson]

Forwardport JDK 20 -> JDK 21

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Commit messages:
 - Merge remote-tracking branch 'jdk20/master' into Merge_jdk20
 - 8299476: PPC64 Zero build fails after JDK-8286302
 - 8293824: gc/whitebox/TestConcMarkCycleWB.java failed "RuntimeException: assertTrue: expected true, was false"
 - 8299483: ProblemList java/text/Format/NumberFormat/CurrencyFormat.java
 - 8298324: Unable to run shell test with make
 - 8299235: broken link referencing missing id

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - master: https://webrevs.openjdk.org/?repo=jdk&pr=11845&range=00.0
 - jdk20: https://webrevs.openjdk.org/?repo=jdk&pr=11845&range=00.1

Changes: https://git.openjdk.org/jdk/pull/11845/files
  Stats: 299 lines in 28 files changed: 101 ins; 131 del; 67 mod
  Patch: https://git.openjdk.org/jdk/pull/11845.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11845/head:pull/11845

PR: https://git.openjdk.org/jdk/pull/11845