[llvm] [flang] [libc] [clang] [clang-tools-extra] [clang][Sema] Populate function template depth at AddTemplateOverloadCandidate (PR #80395)

[Younan Zhang via cfe-commits]

zyn0217 wrote:

Thanks for the quick review!
I tested the original bug report without the patch but couldn't reproduce it. Nevertheless, the example produced by @royjacobson (which still crashes the trunk) was fixed by this patch. 
I'm not sure if this merits a backport?

https://github.com/llvm/llvm-project/pull/80395