Adding a new thread model to GCC

[Eric Botcazou]

> I have faced with "#error Timed lock primitives are not supported on
> Windows targets" and I'm not sure I understood the reason correctly.
> 
> as far as I understand, the definition for
> `_GTHREAD_USE_MUTEX_TIMEDLOCK` comes from libstdc++/configure as a
> result of some test.
> 
> why did I faced with this error? what should I do to avoid this?

Run autoheader + autoconf in the libstdc++-v3 source repository.

-- 
Eric Botcazou