[clang] [clang] check deduction consistency when partial ordering function templates (PR #100692)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

Oh cool, this is CWG2398 TTP-on-Class, this is fixed by https://github.com/llvm/llvm-project/pull/94981 :)

On the SPEC source code side, this is probably similar to the xtensor breakage we got a while ago, there is probably a macro guard somewhere that should be expanded to cover clang.

https://github.com/llvm/llvm-project/pull/100692