[Bug libstdc++/113099] locale without RTTI uses dynamic_cast before gcc 13.2 or has ODR violation since gcc 13.2

[pdimov at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113099

--- Comment #7 from Peter Dimov <pdimov at gmail dot com> ---
You don't necessarily need dynamic_cast because facets are always installed and
obtained by their exact type, not via a reference to base. You can store the
Facet* as given (like shared_ptr does), and return it.

The only reason dynamic_cast is needed here is because you can't static_cast
from facet* to Facet* when virtual inheritance. But you are not required to
store facet* in the actual container; you can store the original Facet* as
void*.