[Bug libstdc++/108225] canadian compilation of gdb error for libstdc++'s std_mutex.h on x86_64-w64-mingw32 host

[unlvsur at live dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108225

--- Comment #18 from cqwrteur <unlvsur at live dot com> ---
(In reply to cqwrteur from comment #17)
> (In reply to Eric Botcazou from comment #16)
> > > #if _WIN32_WINNT >= 0x0600
> > > #define __GTHREAD_HAS_COND 1
> > > #define __GTHREADS_CXX0X 1
> > > #endif
> > > 
> > > I suggest remove this macro in the header due to potential breakage
> > > 
> > > #if _WIN32_WINNT >= 0x0600
> > > #endif
> > 
> > That's nonsensical.
> 
> The problem is that libstdc++ would instantly break if someone randomly
> defines _WIN32_WINNT (like gdb does).

The solution would probably be for libstdc++ to guard against
__GHTREAD_HAS_COND instead