[clang] [Clang] No longer reject call expression whose type is a not-yet-deduced auto type. (PR #208007)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

> If people have ideas how to improve that, we can always do so in follow up work :)

Might have been a good idea to wait before merging, since there is unaddressed feedback and we barely had any time to look over this.

https://github.com/llvm/llvm-project/pull/208007