Integrate LLVM at llvm/llvm-project@19a3e24803a6
Integrate LLVM at llvm/llvm-project@19a3e24803a6

Updates LLVM usage to match
[19a3e24803a6](https://github.com/llvm/llvm-project/commit/19a3e24803a6)

PiperOrigin-RevId: 401373307

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