Integrate LLVM at llvm/llvm-project@def8b952ebc0
Integrate LLVM at llvm/llvm-project@def8b952ebc0

Updates LLVM usage to match
[def8b952ebc0](https://github.com/llvm/llvm-project/commit/def8b952ebc0)

PiperOrigin-RevId: 415513790

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