server: Don't stop writing agent data to the guest when the client disconnects
server: Don't stop writing agent data to the guest when the client disconnects

write_to_vdi_port() was checking for reds->agent_state.connected to determine
wether it could write queued data. But agent_state.connected reflects if
*both* ends are connected. If the client has disconnected, but the guest agent
is still connected and some data is still pending (like a final clipboard
release from the client), then this data should be written to the guest agent.

mathslinux/spice,elmarco/spice,mathslinux/spice,freedesktop-unofficial-mirror/spice__spice,fgouget/spice,ya-mouse/spice,alon/spice-server,dezelin/spice,alon/spice-server,elmarco/spice,dezelin/spice,SPICE/spice,dezelin/spice,SPICE/spice,Fantu/spice,fgouget/spice,mathslinux/spice,freedesktop-unofficial-mirror/spice__spice,Fantu/spice,Fantu/spice,dezelin/spice,freedesktop-unofficial-mirror/spice__spice,mathslinux/spice,alon/spice-server,elmarco/spice,freedesktop-unofficial-mirror/spice__spice,ya-mouse/spice,alon/spice-server,alon/spice-server,SPICE/spice,mathslinux/spice,Fantu/spice,ya-mouse/spice,freedesktop-unofficial-mirror/spice__spice,elmarco/spice,fgouget/spice,fgouget/spice,dezelin/spice,elmarco/spice