[clang] [Clang][Sema] Require `BaseClass::` (not other classes) in member using-declaration in C++98 mode (PR #143492)

[Yanzuo Liu via cfe-commits]

zwuis wrote:

> > I think we need an entry in "Potentially breaking changes" section.
> 
> This is still missing.

I think [this commit](https://github.com/llvm/llvm-project/commit/c9e11f8d3d2c277fca8ec986b0c01ac71e0e4161) move the release note to the right place. Can you check this again?

https://github.com/llvm/llvm-project/pull/143492