Integrate LLVM at llvm/llvm-project@134723edd5bf
Integrate LLVM at llvm/llvm-project@134723edd5bf

Adjusted libcxx BUILD files for
https://github.com/llvm/llvm-project/commit/2ec672dcdf4b72523bbee50c2be0d02fc38be660

Updates LLVM usage to match
[134723edd5bf](https://github.com/llvm/llvm-project/commit/134723edd5bf)

PiperOrigin-RevId: 380542043

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