message: Integrate LLVM at llvm/llvm-project@6878be5dc3ec
  Updates LLVM usage to match
  [6878be5dc3ec](https://github.com/llvm/llvm-project/commit/6878be5dc3ec)
diff: @@ -4,8 +4,8 @@ load("//third_party:repo.bzl", "tf_http_archive")
  def repo(name):
  """Imports LLVM."""
  - LLVM_COMMIT = "e9e788d145f57bcf815b9797191c1560ba39b842"
  - LLVM_SHA256 = "8eb4506d1bcd039c6a9bac59d7b291349fff2726a47959395daf921e84c8b687"
  + LLVM_COMMIT = "6878be5dc3ec7031d0deec3e321310115bd71103"
  + LLVM_SHA256 = "f55187a3329fd97fd62fd0714783524d50a3be934a35484bd4442195fb25f0e5"
  tf_http_archive(
  name = name,
  