[PartialInlining] Use DenseSet instead of DenseMap (NFC)#127170

kazutakahirata merged 2 commits intollvm:mainllvm/llvm-project:mainfrom

kazutakahirata:cleanup_001_repeated_hash_lookups_llvm_PartialInliningkazutakahirata/llvm-project:cleanup_001_repeated_hash_lookups_llvm_PartialInliningCopy head branch name to clipboard