[llvm] [LSR] Provide TTI hook to enable dropping solutions deemed to be unprofitable (PR #89924)

[Michael Kruse via llvm-commits]

https://github.com/Meinersbur approved this pull request.

LGTM.

Which targets are going to override `shouldDropLSRSolutionIfLessProfitable`?

https://github.com/llvm/llvm-project/pull/89924