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

[via llvm-commits]

ronlieb wrote:

llvm.org main branch,  lots of projects .  i am building with these enabled 
-DLLVM_ENABLE_PROJECTS="clang;lld;clang-tools-extra;flang" 
-DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi;openmp;offload;compiler-rt;libunwind" 


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