[PATCH,RFC] Change __convert_from_v to use snprintf and use it

[Benjamin Kosnik]

> I see. I think that the scheme using snprintf is so much better than the 
> current one that it is worth a temporary rough solution from the point 
> of view of the autoconf. What about working together on the autoconf 
> bits, if and when the new locale_facets code is ready and well tested?

I think this sounds like a good idea. If it turns out that the macro 
guard should be _GLIBCPP_HAVE_SNPRINTF then so be it.

-benjamin