[Patch] Fix libstdc++/11740

[Paolo Carlini]

B. Kosnik wrote:

>...gotta do the generic locale too,
>
It's already in the patch.

> and might as well check ctype<char>
>for this same thing, since it's probably wrong too. (At least the
>ctype<char> is generic locale).
>
Those are ok, because are table-based.

>I believe I moved this bit over to 3.3 branch, so move this over too...
>
Ok, will do after a day of testing...
Paolo.