[NFC][Clang][TableGen] Use StringRef in FlattenedSpelling#113809

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

jurahul:clang_attr_emitter_flttened_spelling_stringrefjurahul/llvm-project:clang_attr_emitter_flttened_spelling_stringrefCopy head branch name to clipboard