Integrate LLVM at llvm/llvm-project@fffd966f0b0f
Integrate LLVM at llvm/llvm-project@fffd966f0b0f

Updates LLVM usage to match
[fffd966f0b0f](https://github.com/llvm/llvm-project/commit/fffd966f0b0f)

PiperOrigin-RevId: 470832346

google-research/structured-additive-IR,google-research/structured-additive-IR