[clang] [Clang] Add support for GCC bound member functions extension (PR #135649)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

I am going to chime in, in support of both Aaron's and Erich's position here. This does not seem like an extension we want to support.

So given the objections, we need at minimum an RFC and see how that goes. Maybe during that discussion a more compelling case can be made.

https://github.com/llvm/llvm-project/pull/135649