[clang] Add test for CWG1111

Also mark [[ https://wg21.link/cwg2385 | CWG2385 ]] as `na`, because it eliminates wording inconsistency introduced by [[ https://wg21.link/cwg1111 | CWG1111 ]] resolution.

Reviewed By: #clang-language-wg, erichkeane

Differential Revision: https://reviews.llvm.org/D142315