[clang] [clang] Alias cc modifier to c (PR #127719)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

It seems like for gcc at least, IIUC, `cc` does a bit more than `c` so while we are supporting `cc` for compatibility we are not fully supporting it? Specifically:

`except try harder to print it with no punctuation`

Perhaps we should document that in the comment in `Stmt.cpp`, for gcc comparability but not totally equivalent? 

https://github.com/llvm/llvm-project/pull/127719