RFR: Merge jdk18

[Jesper Wilhelmsson]

Forwardport JDK 18 -> JDK 19

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Commit messages:
 - Merge remote-tracking branch 'jdk18/master' into Merge_jdk18
 - 8271202: C1: assert(false) failed: live_in set of first block must be empty
 - 8279195: Document the -XX:+NeverActAsServerClassMachine flag
 - 8278889: AArch64: [vectorapi] VectorMaskLoadStoreTest.testMaskCast() test fail

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - master: https://webrevs.openjdk.java.net/?repo=jdk&pr=6936&range=00.0
 - jdk18: https://webrevs.openjdk.java.net/?repo=jdk&pr=6936&range=00.1

Changes: https://git.openjdk.java.net/jdk/pull/6936/files
  Stats: 509 lines in 40 files changed: 418 ins; 0 del; 91 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6936.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6936/head:pull/6936

PR: https://git.openjdk.java.net/jdk/pull/6936