[llvm] Greedy: Make eviction broken hint cost use CopyCost units (PR #160084)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> Basic idea here seems entirely reasonable. Can you update the comment in the header?

> is applying to the possible future change, not this one right? I think so, but the wording got slightly confusing, and I don't want to get this backwards.

Yes, this is the minimum viable patch that shows something, the problems are in fixing the double counting bug 

https://github.com/llvm/llvm-project/pull/160084