Integrate LLVM at llvm/llvm-project@51ff04567b2f
Integrate LLVM at llvm/llvm-project@51ff04567b2f

Updates LLVM usage to match
[51ff04567b2f](https://github.com/llvm/llvm-project/commit/51ff04567b2f)

PiperOrigin-RevId: 337477820

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