Simpify transparent_less_nonempty

Author: frederick-vs-ja

libcxx/test/support/is_transparent.h

@@ -40,10 +40,8 @@ struct transparent_less_not_referenceable
 // See https://github.com/llvm/llvm-project/issues/152543.
 struct transparent_less_nonempty {
   template <class T, class U>
-  constexpr auto operator()(T&& t, U&& u) const                   //
-      noexcept(noexcept(std::forward<T>(t) < std::forward<U>(u))) //
-      -> decltype /**/ (std::forward<T>(t) < std::forward<U>(u)) {
-    return /*--------*/ std::forward<T>(t) < std::forward<U>(u);
+  constexpr bool operator()(T&& t, U&& u) const {
+    return std::forward<T>(t) < std::forward<U>(u);
   }
   struct is_transparent {
   } pad_; // making this comparator non-empty