[llvm] AMDGPU: Replace sqrt OpenCL libcalls with llvm.sqrt (PR #74197)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> Any codegen changes except IR? It is hard to reason looking at IR only.

The IR change is the point. The only meaningful codegen tests would be an end-to-end test which also links the libraries in. There's nothing to really test for codegen, other than this can now be directly codegened into a working program.

https://github.com/llvm/llvm-project/pull/74197