[Bug libstdc++/88339] Implement P0515R3, C++20 three-way comparison operator support .

[emsr at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88339

--- Comment #2 from emsr at gcc dot gnu.org ---
-// std::initializer_list support -*- C++ -*-
+// Three-way comparison support -*- C++ -*-