Fence Sync patches

[James Jones]

As I mentioned early on, I really want to get the fence sync work in server 
1.10.  The server code was reviewed by Adam Jackson (thanks for sifting 
through all that) and various nvidians, but I still haven't received any  
external official reviewed-by for the proto updates it relies on, or for the lib 
code to exercise it.  I've CC'd the suggested reviewers on the latest versions 
of the patches and here:

-Alan and Adam, because you provided some early feedback on the proto specs 
but never responded to my updates based on said feedback.

-Keith, because you're the maintainer of the damage subsystem, and there are 
some minor changes to the damage proto and lib.

If these remaining pieces get reviewed, I can send out pull requests for 
everything immediately.  I've had this code out for review in some form for 
about 3 months now, so it'd be pretty disappointing if it had to sit around 
waiting for another release cycle.

Thanks,
-James