RFR: Merge openjdk/jdk21u-dev:master

[William Kemper]

Merges tag jdk-21.0.3+3

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Commit messages:
 - 8325194: GHA: Add macOS M1 testing
 - 8324753: [AIX] adjust os_posix after JDK-8318696
 - 8323671: DevKit build gcc libraries contain full paths to source location
 - 8323667: Library debug files contain non-reproducible full gcc include paths
 - 8318039: GHA: Bump macOS and Xcode versions
 - 8325150: (tz) Update Timezone Data to 2024a
 - 8309109: AArch64: [TESTBUG] compiler/intrinsics/sha/cli/TestUseSHA3IntrinsicsOptionOnSupportedCPU.java fails on Neoverse N2 and V1
 - 8324637: [aix] Implement support for reporting swap space in jdk.management
 - 8324598: use mem_unit when working with sysinfo memory and swap related information
 - 8323964: runtime/Thread/ThreadCountLimit.java fails intermittently on AIX
 - ... and 14 more: https://git.openjdk.org/shenandoah-jdk21u/compare/2518d203...b9cf41da

The webrev contains the conflicts with master:
 - merge conflicts: https://webrevs.openjdk.org/?repo=shenandoah-jdk21u&pr=21&range=00.conflicts

Changes: https://git.openjdk.org/shenandoah-jdk21u/pull/21/files
  Stats: 1787 lines in 95 files changed: 1192 ins; 374 del; 221 mod
  Patch: https://git.openjdk.org/shenandoah-jdk21u/pull/21.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah-jdk21u.git pull/21/head:pull/21

PR: https://git.openjdk.org/shenandoah-jdk21u/pull/21