[llvm] [LV] Scale block costs using BranchFrequencyInfo (PR #71793)

[Simeon K via llvm-commits]

simeonkr wrote:

@nikic We may need to revert https://github.com/llvm/llvm-project/commit/4bc254c66442ce64075eb257105fb89e53e8a89f for this to be useful.

https://github.com/llvm/llvm-project/pull/71793