[lworld+fp16] RFR: Merge lworld

[Jatin Bhateja]

Merge latest lworld code into lworld+fp16.

All existing Float16 tests are passing post merge.

Best Regards,
Jatin

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Commit messages:
 - Merge branch 'lworld' of http://github.com/openjdk/valhalla into merge_lworld2fp16
 - 8336782: [lworld] CallStaticJavaNode::remove_useless_allocation does not handle dying subgraph
 - 8336842: [lworld] Return value buffering in TLAB does not work with -XX:FastAllocateSizeLimit=0
 - 8326605: [lworld] SplitIfSharedFastLockBehindCastPP performs synchronization on a value class
 - 8336837: [lworld] Invalid monitor information in JVMState when buffering at return
 - 8337747: [lworld] Refactor Loop Unswitching code after merging in JDK-8325746
 - 8338252: [lworld] jdk/internal/ReferencedKeyTest fix merge and robustness
 - 8336778: [lworld] C2 compilation hits "invalid node class" assert when merging object field values
 - Merge jdk
 - 8329178: Clean up jdk.accessibility native compilation
 - ... and 751 more: https://git.openjdk.org/valhalla/compare/be93540f...ca179277

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - lworld+fp16: https://webrevs.openjdk.org/?repo=valhalla&pr=1213&range=00.0
 - lworld: https://webrevs.openjdk.org/?repo=valhalla&pr=1213&range=00.1

Changes: https://git.openjdk.org/valhalla/pull/1213/files
  Stats: 527146 lines in 6066 files changed: 66202 ins; 122781 del; 338163 mod
  Patch: https://git.openjdk.org/valhalla/pull/1213.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1213/head:pull/1213

PR: https://git.openjdk.org/valhalla/pull/1213