[llvm] [InstCombine] Sink widening casts used only by extractelements (PR #201529)

[via llvm-commits]

https://github.com/azwolski requested changes to this pull request.

I would change the multi-use case to require every extract user to satisfy the same sinkability/profitability condition, for example:
```

https://github.com/llvm/llvm-project/pull/201529