[llvm] [ADT] Deprecate the redirection from SmallSet to SmallPtrSet (Take 2) (PR #155078)

[Scott Manley via llvm-commits]

rscottmanley wrote:

Note, this is also still in the docs: https://llvm.org/docs/ProgrammersManual.html#llvm-adt-smallset-h

https://github.com/llvm/llvm-project/pull/155078