Integrate LLVM at llvm/llvm-project@51a292d99453
Integrate LLVM at llvm/llvm-project@51a292d99453

Updates LLVM usage to match
[51a292d99453](https://github.com/llvm/llvm-project/commit/51a292d99453)

PiperOrigin-RevId: 349610524

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