[Patch] Fix libstdc++/9404 (and all that)

[pcarlini@unitus.it]

Quoting Benjamin Kosnik <bkoz@redhat.com>:

>Shall we put this in?
> 
> I think you should put this in! Thanks. This looks good.

Fine.
By the way, this fixes the first half of libstdc++/9701 too.

Paolo.