[clang] [Clang][Sema] Use the correct lookup context when building overloaded 'operator->' in the current instantiation (PR #104458)

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cor3ntin wrote:

> > I think there won't be a rc4 so it's actually probably too late
> 
> You have the wrong handle, on github it's @tru. 😉 Also, RC4 is being [considered](https://discourse.llvm.org/t/llvm-19-1-0-final-update-and-possible-rc4/81010).

Thanks! However we can't consider a backport until we have something to backport!

https://github.com/llvm/llvm-project/pull/104458