Integrate LLVM at llvm/llvm-project@6f9c25167d16
Integrate LLVM at llvm/llvm-project@6f9c25167d16

Updates LLVM usage to match
[6f9c25167d16](https://github.com/llvm/llvm-project/commit/6f9c25167d16)

PiperOrigin-RevId: 406199997

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