[jdk21u-dev] RFR: Merge jdk21u:master

[Goetz Lindenmaier]

Merge build tag 21.0.8+6 from jdk21u to jdk21u-dev

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

Commit messages:
 - Merge
 - 8357105: C2: compilation fails with "assert(false) failed: empty program detected during loop optimization"

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

Changes: https://git.openjdk.org/jdk21u-dev/pull/1865/files
  Stats: 66 lines in 2 files changed: 64 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1865.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1865/head:pull/1865

PR: https://git.openjdk.org/jdk21u-dev/pull/1865