[Xcb] GIT repo split - please test

[Russell Shaw]

Vincent Torri wrote:
> 
> I have done a check out of proto, libxcb, util and demo. No problem with 
> the check out.
> 
> But there is always that error with xcb_get_request_read, that must be 
> changed with poll_for_event, iirc. I don't really know how to do that, 
> though.

I've been wondering how to fix it, but it's not easy when learning
xcb at the same time;)