Integrate LLVM at llvm/llvm-project@b5149f4e66a4
Integrate LLVM at llvm/llvm-project@b5149f4e66a4

Updates LLVM usage to match
[b5149f4e66a4](https://github.com/llvm/llvm-project/commit/b5149f4e66a4)

PiperOrigin-RevId: 419786634

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