[jdk21u-dev] RFR: 8294316: SA core file support is broken on macosx-x64 starting with macOS 12.x

Thu Dec 12 15:59:53 UTC 2024

A clean backport of [JDK-8294316](https://bugs.openjdk.org/browse/JDK-8294316) to properly parse core files in macOS 12 and later.  Load commands with length zero are now discarded. 

The fix doesn't affect directly to SA tests in `21`, but it's being backported to `11` as this is the cause of [an older version of `serviceability/sa/ClhsdbFindPC.java` failing in JDK 11 on macos-13 GHA runners](https://github.com/openjdk/jdk11u-dev/pull/2967#issuecomment-2538048579). 

Tests in 21 continue to pass in all platforms, including `macos`.

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Commit messages:
 - Backport 269852b90634aa43d4d719c93563608e42792fc6

Changes: https://git.openjdk.org/jdk21u-dev/pull/1227/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1227&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8294316
  Stats: 17 lines in 2 files changed: 5 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1227.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1227/head:pull/1227

PR: https://git.openjdk.org/jdk21u-dev/pull/1227