libstdc++ compatibility

[Joe Buck]

>   > Evidently this point is an issue for Red Hat: they don't want to ship
>   > egcs-1.1 because it breaks binary compatibility with egcs-1.0.x, for
>   > this reason.
>   > 
>   > I suppose Red Hat could patch 1.1 to generate thread-unsafe exceptions
>   > in a way that gives compatibility with 1.0.x.
> That's a good question!
> 
> If there's not any other binary compatibility problems disabling thread
> support at configure time may give Red Hat a way to upgrade from egcs-1.0.3.

Any Red Hat folks reading this?  It would be nice to have a version that
you don't have to patch (give you the right configuration options
instead).