We add a new clang library called clangSupport for putting those utils which can be used in clang table-gen and other clang component.
We tried to put that into llvm/Support, but actually those stuffs only used in clang* and clang-tblgen, so I think that might be better to create clang/Support
- clang will used that in https://reviews.llvm.org/D111617.
Comment here seems off (this isn't a .cpp file, it's a .h)