[llvm] [InlineCost] Allow simplifying to non-Constant values (PR #145083)

[Tobias Stadler via llvm-commits]

tobias-stadler wrote:

> Is this NFC? Or could you add a test?

Yes, this should be NFC until we start using getSimplifiedValueUnchecked or start mapping Instructions to non-Constant.

https://github.com/llvm/llvm-project/pull/145083