[Patch] Fix libstdc++/9439 and libstdc++/9425

[Paolo Carlini]

Benjamin Kosnik wrote:

>>Tested x86-linux, as usual. Ok for trunk? 3_3 too?
>>
>Looks great Paolo, thanks again.
>
Thanks to you.

>At some point, somebody will have to go through and convert the 27_io
>tests to the 22_locale style. I think it's ok for you to just add this
>the way you have it, at this point.
>
Fiuuu... ;)

Seriously, I can imagine that this should be done, but it's quite a bit
of work and I have already on my desktop (besides that famous long row
of empty coffe mugs...) libstdc++/9548, Sebor's nasty locale issues,
and 3-4 other PRs and pending works...

Ciao,
Paolo.