Building libstdc++-v3 and -WError

[Benjamin Kosnik]

> Unfortunately, I'm not sure to see how Branko's patch will solve it 
> (this definitely does not imply that the patch is not useful).

Right. It should go in because it is useful, and will be more useful in 
the future.

> Anyhow, it seems that this will find some solution if not the best 
> solution, so thanks to all of you.

Phil has graciously made a patch to disable -Werror by default, and 
enable it as part of --enable-maintainer-mode. This approach seems to be 
favored by most people, so it's going to go in......

I've also removed yesterday's hack.

-benjamin