Integrate LLVM at llvm/llvm-project@506df1bbfd16
Integrate LLVM at llvm/llvm-project@506df1bbfd16

Updates LLVM usage to match
[506df1bbfd16](https://github.com/llvm/llvm-project/commit/506df1bbfd16)

PiperOrigin-RevId: 363377317

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