Integrate LLVM at llvm/llvm-project@6cffc35746b4
Integrate LLVM at llvm/llvm-project@6cffc35746b4

Updates LLVM usage to match
[6cffc35746b4](https://github.com/llvm/llvm-project/commit/6cffc35746b4)

PiperOrigin-RevId: 399646495

tensorflow/runtime,tensorflow/runtime,tensorflow/runtime,tensorflow/runtime