[clang] [Clang] Fix infinite loop on '::' inside parens in C mode (PR #195377)

[Petr Beneš via cfe-commits]

wbenny wrote:

> I wonder if there are other places where we assume that a `::` token only exists in C++.

I didn't find any other places.

Is there anything else I could help with this PR? Is there any chance this would get into 23.x?

https://github.com/llvm/llvm-project/pull/195377