Integrate LLVM at llvm/llvm-project@86cdb2929cce
Integrate LLVM at llvm/llvm-project@86cdb2929cce

Updates LLVM usage to match
[86cdb2929cce](https://github.com/llvm/llvm-project/commit/86cdb2929cce)

PiperOrigin-RevId: 443131797

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