Integrated: Merge jdk19

[David Holmes]

Forward port JDK 19 -> JDK 20

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Commit messages:
 - Merge remote-tracking branch 'jdk19/master' into Merge_jdk19
 - 8291006: java/foreign/TestUnsupportedPlatform fails after JDK-8290455
 - 8290455: jck test api/java_lang/foreign/VaList/Empty.html fails on some platforms
 - 8290460: Alpine: disable some panama tests that rely on std::thread

The merge commit only contains trivial merges, so no merge-specific webrevs have been generated.

Changes: https://git.openjdk.org/jdk/pull/9656/files
  Stats: 134 lines in 4 files changed: 67 ins; 52 del; 15 mod
  Patch: https://git.openjdk.org/jdk/pull/9656.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9656/head:pull/9656

PR: https://git.openjdk.org/jdk/pull/9656