[clang] [clang-format] Fix a bug in annotating function declaration names (PR #76206)

[Björn Schäpers via cfe-commits]

HazardyKnusperkeks wrote:

> > `clang-format` doesn't know what are types, except for the keywords. So there is no way to decide if this is a function declaration without naming the parameters, or a variable declaration with a constructor call.
> 
> This is C so I guess it can only be a function declaration. Anyway, it's minor to work around, thanks again.

This boils down to, that for `clang-format` C doesn't exist. It's all parsed as C++.

https://github.com/llvm/llvm-project/pull/76206