message: Integrate LLVM at llvm/llvm-project@51ff04567b2f
  Updates LLVM usage to match
  [51ff04567b2f](https://github.com/llvm/llvm-project/commit/51ff04567b2f)
diff: @@ -712,8 +712,8 @@ def tf_repositories(path_prefix = "", tf_repo_name = ""):
  )
  # Check out LLVM and MLIR from llvm-project.
  - LLVM_COMMIT = "cfa7094e49cfb7e37a84c0aa57c85c64c0581d17"
  - LLVM_SHA256 = "508dfe956f261f32a4e723f645235dbaf3907da09bdecd9e93f05edd809ad06a"
  + LLVM_COMMIT = "51ff04567b2f8d06b2062bd3ed72eab2e93e4466"
  + LLVM_SHA256 = "04be63368fea3b904b8467d5636a22ef38daacf299c807dc7a8f881800a1ee35"
  LLVM_URLS = [
  "https://storage.googleapis.com/mirror.tensorflow.org/github.com/llvm/llvm-project/archive/{commit}.tar.gz".format(commit = LLVM_COMMIT),
  "https://github.com/llvm/llvm-project/archive/{commit}.tar.gz".format(commit = LLVM_COMMIT),
  