[Patch] Fix libstdc++/10097

[Benjamin Kosnik]

Yo Paolo, this looks good. Please make the created temporary files in
the testsuite start with tmp_*: see my last check in. Other than that, cool.

>Tested x86-linux. If approved, seems good for 3.3 too.
>
>In general, my plans are as follows:
>
>  1- Have in fixes for 9533 and 10097: proposals already
>     posted.

I'll get to the showmany one tomorrow.

>  2- Have in Pétur's patches for 9964, 9581/9870: both
>     ok with me!

In.

>  3- Return to 9701 to fix the second part: seems easy in
>     the light of some obervations from Nathan.
>  4- Finally return to 9423/9024, and then 9875/9178.

I would really like to investigate the idea of completely separate
unbuffered/buffered filebuf classes for narrow and wide input. Petur
proposed a wide one, but I think it's the way to go for both. I'll work
on doing this, or at least a proof of concept, or getting to the point
where I can explain it.

I really need to fix up the 27 testsuites. Ugh. If I do that, would you
please consider doing 21 in parallel? Ugh. If we both work on it I bet
we could get both done in the next week. Would you please, please
consider doing this important work with me this week instead? I really
need help with this, and you are the 21_strings maintainer. Or, we could
flip for it and the one who loose could do 27.

-benjamin