[llvm] [SLP]Support revectorization of the previously vectorized scalars (PR #133091)

[Alexander Kornienko via llvm-commits]

alexfh wrote:

Sent https://github.com/llvm/llvm-project/pull/134604. I'll land it as soon as the premerge checks finish.

https://github.com/llvm/llvm-project/pull/133091