RFR: Merge openjdk/jdk21u-dev:master

[William Kemper]

Merges tag jdk-21.0.4+3

-------------

Commit messages:
 - 8324243: Compilation failures in java.desktop module with gcc 14
 - 8311964: Some jtreg tests failing on x86 with error 'unrecognized VM options' (C2 flags)
 - 8321925: sun/security/mscapi/KeytoolChangeAlias.java fails with "Alias <246810> does not exist"
 - 8320370: NMT: Change MallocMemorySnapshot to simplify code.
 - 8325621: Improve jspawnhelper version checks
 - 8330524: Linux ppc64le compile warning with clang  in os_linux_ppc.cpp
 - 8330523: Reduce runtime and improve efficiency of KeepAliveTest
 - 8330815: Use pattern matching for instanceof in KeepAliveCache

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

Changes: https://git.openjdk.org/shenandoah-jdk21u/pull/45/files
  Stats: 1346 lines in 21 files changed: 140 ins; 1028 del; 178 mod
  Patch: https://git.openjdk.org/shenandoah-jdk21u/pull/45.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah-jdk21u.git pull/45/head:pull/45

PR: https://git.openjdk.org/shenandoah-jdk21u/pull/45