[PATCH] 4.0 fix for libstdc++/23871

[Paolo Carlini]

Janis Johnson wrote:

>Paolo and Benjamin have both said offline that this backport from
>mainline to the 4.0 branch (when it reopens) is OK, but this is the
>first time I've written a test for libstdc++; is this the right
>location for it, and does it need anything else in the comments?
>
I would suggest simply adding the testcases that originally went in
together with those bits of the patch. In other terms,
testsuite/27_io/basic_ostream/inserters_arithmetic/char/7.cc and
testsuite/27_io/basic_ostream/inserters_arithmetic/wchar_t/7.cc
(actually the bits for long and long long should pass already, please
double check).

Paolo.