3.1.1 PATCH: Fix libstdc++-v3 isprint for Solaris 2.5.1

[Rainer Orth]

Gerald Pfeifer writes:

> > This is not a regression since the test was only introduced after the 3.1
> > release, but it's a stupid bug and trivial to fix:
> 
> Just to make sure:  A regression is when a current version of GCC fails to
> correctly process a program that an earlier version of GCC processed fine.
> 
> "Program" here is not limited to programs that were already part of the
> testsuite of that earlier version of GCC, it can also be a completely new
> testcase.

Unfortunately, the bug is already present in the 3.0 branch and 2.95.x
libstdc++ didn't provide the interface.

Anyway, the patch may qualify as obvious and low-risk even for 3.1.1, since
it only affects Solaris 2.5.

	Rainer