[llvm] [Inliner][TTI][AMDGPU] Add size growth TTI hook for unreachable-termed bb (PR #217014)

[Janek van Oirschot via llvm-commits]

JanekvO wrote:

In that case, I'll go with the TTI'ing `allowSizeGrowth` altogether approach. For context, I was looking for a non-intrusive way to elide the inlining but no other inliner TTI precedes it s.t. I can affect the costs (nor was I able to find an existing TTI that would suitably be fit for purpose here).

https://github.com/llvm/llvm-project/pull/217014