Couple of new issues in mainline

[Benjamin Kosnik]

> ... and something breaks: turns out we have in the ABI baseline quite a 
> few inlines, see below. We should analyze this issue more in detail. 
> Something I don't fully understand is going on with the std exception 
> classes destructors, which are indeed trivial but *not* inline: those 
> appear as 'W' in stdexcept.o, but as 't' in the final .so (thus in the 
> below). Similarly for ~basic_stringbuf, synthetized by the compiler, it 
> appear as 'W' in sstream-inst.o and as 't' in the .so. It looks like 
> this 'W' -> 't' change is the visibility fall-out of a link-time 
> optimization, which at the moment I don't fully understand (help in 
> clarifying this issue would be particularly appreciated)

For the stdexcept destructor issue, see the "This declaration is not
useless" comment in <new>. This is done to collect the exception class
vtables into one file.

-benjamin