[clang] Reapply "[clang] Fix name lookup for dependent bases" (PR #118003)

[Vladislav Belov via cfe-commits]

vbe-sc wrote:

> I was creducing it (well, cvise-ing). Here's a reproducer:
> 
> ```
> template <typename, typename, bool> struct MozPromise {
>   class Private;
> 
> private:
>   void *mMagic4;
> };
> template <typename ResolveValueT, typename RejectValueT, bool IsExclusive>
> struct MozPromise<ResolveValueT, RejectValueT, IsExclusive>::Private
>     : MozPromise {
>   void SetTaskPriority() { mMagic4 }
> }
> ```

Thanks, I'll investigate with it 

https://github.com/llvm/llvm-project/pull/118003