Integrate LLVM at llvm/llvm-project@68f66f37d7d7
Integrate LLVM at llvm/llvm-project@68f66f37d7d7

Updates LLVM usage to match
[68f66f37d7d7](https://github.com/llvm/llvm-project/commit/68f66f37d7d7)

PiperOrigin-RevId: 355069626

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