streaming: Stop streaming if the client reports a streaming error
streaming: Stop streaming if the client reports a streaming error

By removing the stream's video encoder we force the stream to send
future frames using the fallback code, that is as regular screen
updates.
However note that we keep the stream object: we have to. Otherwise
future frames would trigger the creation of a new stream object with a
new video encoder which would again try to stream the video and fail
again and again.

Signed-off-by: Francois Gouget <6b915da68578f6eb004fe99432b967565fc9be8f@codeweavers.com>
Acked-by: Christophe Fergeau <05b95054a663c388a4e33d95828cb30f0370f8ef@redhat.com>
Reviewed-by: Victor Toso <39b7599ff73bbf5db531748ba5250f21fa7120ff@redhat.com>

fgouget/spice,fgouget/spice,fgouget/spice,fgouget/spice