RFR: Merge openjdk/jdk:master

[William Kemper]

Merge tag jdk-21+8

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Commit messages:
 - Use new parallel_threads_do to handle claim tokens
 - ZZMerge tag 'jdk-21+8' into merge-jdk-21-8
 - 8294527: Some java.security.debug options missing from security docs
 - 8301447: [REDO] CodeHeap has virtual methods that are not overridden
 - 8295486: Inconsistent constant field values observed during compilation
 - 8301093: C2 fails assert(ctrl == kit.control()) failed: Control flow was added although the intrinsic bailed out
 - 8300256: C2: vectorization is sometimes skipped on loops where it would succeed
 - 8301402: os::print_location gets is_global_handle assert
 - 8301446: Remove unused includes of gc/shared/genOopClosures
 - 8301459: Serial: Merge KeepAliveClosure into FastKeepAliveClosure
 - ... and 109 more: https://git.openjdk.org/shenandoah/compare/75811f96...89cd21a5

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - master: https://webrevs.openjdk.org/?repo=shenandoah&pr=216&range=00.0
 - openjdk/jdk:master: https://webrevs.openjdk.org/?repo=shenandoah&pr=216&range=00.1

Changes: https://git.openjdk.org/shenandoah/pull/216/files
  Stats: 16090 lines in 821 files changed: 3884 ins; 2289 del; 9917 mod
  Patch: https://git.openjdk.org/shenandoah/pull/216.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah pull/216/head:pull/216

PR: https://git.openjdk.org/shenandoah/pull/216