08159e6e11
Identifiers `clang` and `noescape` are not reserved by the C++ standard, so perhaps we need to use the equivalent reserved forms. Also changes the occurrences of that attribute to a macro, following the convention for `[[_Clang::__lifetimebound__]]`. Addresses https://github.com/llvm/llvm-project/pull/91651#discussion_r1807852646.