[llvm] Reland [VectorUtils] Trivially vectorize ldexp, [l]lround (PR #152476)

[Florian Hahn via llvm-commits]

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

LGTM, thanks. The issue that caused the revert has been fixed, should be good to go now

https://github.com/llvm/llvm-project/pull/152476