[Bug libstdc++/127219] <format>: make __valid_types_for_check_dynamic_spec static so check_dynamic_spec<Ts...> works with clang and EDG

[stevensudit at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127219

--- Comment #1 from Steve Sudit <stevensudit at gmail dot com> ---
Created attachment 65508
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=65508&action=edit
reduction without <format>: implicit this in a static_assert (gcc, MSVC accept;
clang, EDG reject)