Modify -mabi=64 C++ Testing

[Benjamin Kosnik]

> I don't have time right now to provide a proper patch, but I hope from the
> information above someone familiar with the libstdc++ v3 testsuite will be
> able to do so.

neither do I.....

I think this is just going to have to remain broken, or get magically 
fixed by somebody else. As you've said, this can be tested manually so I 
regard this as low-priority.

In general, using the libjava approach seems sane.

-benjamin