Integrate LLVM at llvm/llvm-project@fb84aa2a8f52
Integrate LLVM at llvm/llvm-project@fb84aa2a8f52

Updates LLVM usage to match
[fb84aa2a8f52](https://github.com/llvm/llvm-project/commit/fb84aa2a8f52)

PiperOrigin-RevId: 400687370

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