[doc,libstdc++] Links to bogus/spam site

[Paolo Carlini]

Hi,
> We should refrain from linking to beauty, wellness, and cellulite sites,
> I guess. ;-)
>
> I am not an expert as far as the libstdc++ docs goes, so I'd appreciate
> if one of you guys could confirm that this patch is fine.
>   
I would suggest instead replacing the links with either:

    http://www.opengroup.org/onlinepubs/009695399/

or:

    http://www.unix.org/version3/ieee_std.html

Also adjusting 1003.1-200x to 1003.1-2004 and "System Interface
Definitions, Issue 6" to "The Open Group Base Specifications Issue 6".

Thanks,
Paolo.