V3 static data in classes vs AIX

[Benjamin Kosnik]

> AIX complains about _S_max_size as well -- as undefined, not as
> duplicate symbols.

Ahh. Ok. Sorry I wasn't clear: on Tru64 is is also undefined. We must put 
in an explicit instantiation into src/string-inst.cc to solve this for 
both platforms. The undefined symbols are easy to take care of, IMHO.

Still though, Tru64 doesn't have these duplicates, yet AIX does, so the 
inconsistency still exists. Or maybe the Tru64 linker just doesn't care? 

-benjamin