Integrate LLVM at llvm/llvm-project@a1dc6d4b83a3
Integrate LLVM at llvm/llvm-project@a1dc6d4b83a3

Updates LLVM usage to match
[a1dc6d4b83a3](https://github.com/llvm/llvm-project/commit/a1dc6d4b83a3)

PiperOrigin-RevId: 425623542

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