Integrate LLVM at llvm/llvm-project@2fa4186d4e1c
Integrate LLVM at llvm/llvm-project@2fa4186d4e1c

Updates LLVM usage to match
[2fa4186d4e1c](https://github.com/llvm/llvm-project/commit/2fa4186d4e1c)

PiperOrigin-RevId: 356383544

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