tr1::shared_ptr and v3's atomic ops

[Benjamin Kosnik]

> It's probably not the best time.  I certainly would like to have us 
> implement the interface in <ia64intrin.h> generically across all
> architectures[*].  The api seems well thought out, and I know that at
> least SGI implemented these builtins for both ia64 and mips.

Interesting, thanks. It's helpful to know where you think this should end up.

> I'm not sure what kind of timeline there would be on getting these
> builtins though.

Yeah. We've been talking about it for a year now.

-benjamin