[llvm] [AMDGPU] Add getCmpSelInstrCost override to re-enable SimplifyCFG speculation for vector types (PR #208043)

[Frederik Harwath via llvm-commits]

================

----------------
frederik-h wrote:

I agree regarding the new cost model test, but note that the changes to those tests are just restoring the state from before the commit that made the base cost model changes which caused the regression for AMDGPU (0967957d7a94e1b5c749c6e963bdca25f3c6d749).

https://github.com/llvm/llvm-project/pull/208043