[Bug libstdc++/108331] [13 Regression] ABI break of std::__c_file and std::fstream for win32 thread model of GCC for windows

[ebotcazou at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108331

--- Comment #3 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> Eric, can we add a new macro to gthr-win32.h that says "this is the win32
> thread model" which libstdc++ can then use like so:

Sure, but can't we define a __GTHREAD_TYPE_FOR_HISTORICAL_MUTEX macro instead
that would expand to a __gthread_historical_mutex_t defined in gthr-win32.h?
Or something along these lines or with better monikers.