[DebugInfo] Use heterogenous lookups with std::map (NFC)#113118

kazutakahirata merged 1 commit intollvm:mainllvm/llvm-project:mainfrom

kazutakahirata:cleanup_001_heterogenous_DebugInfokazutakahirata/llvm-project:cleanup_001_heterogenous_DebugInfoCopy head branch name to clipboard