include/bits/concurrence.h breaks MinGW bootstrap

[Benjamin Kosnik]

>This is in reference to this post:
>
>http://gcc.gnu.org/ml/libstdc++/2004-06/msg00351.html

This is now libstdc++/16248.

>I was able to unbreak the MinGW bootstrap with the
>attached patch, but I haven't tested it at all. (Just
>take it as a suggestion....) If someone wants me to follow
>up on this, let me know.

Can somebody test and report back please?

-benjamin