rtsp-client: do not free main context before rtsp watch
rtsp-client: do not free main context before rtsp watch

https://bugzilla.gnome.org/show_bug.cgi?id=737110

barisdemiray/gst-rtsp-server,surround-io/gst-rtsp-server,hsteinhaus/gst-rtsp-server,hsteinhaus/gst-rtsp-server,surround-io/gst-rtsp-server,thaytan/gst-rtsp-server,surround-io/gst-rtsp-server,barisdemiray/gst-rtsp-server,thaytan/gst-rtsp-server,hsteinhaus/gst-rtsp-server,barisdemiray/gst-rtsp-server,thaytan/gst-rtsp-server