In case the client isn't responding, this will block the compositor.
Instead we flush with MSG_DONTWAIT, which lets us fill up the kernel buffer
as much as we can (after not returning EPOLLOUT anymore it still can take
80k more), and then disconnect the client if we get EAGAIN.
We set aside a range of the object ID space for use by the server. This
allows the server to bind an object to an ID for a client and pass that
object to the client. The client can use the object immediately and the
server can emit events to the object immdiately.
