Fix ownership of appsink return values
Fix ownership of appsink return values

Patch by kenkela@gmail.com.

Fixes bug #618336.

Forage/gstreamer-sharp,freedesktop-unofficial-mirror/gstreamer__gstreamer-sharp,GStreamer/gstreamer-sharp,gstreamer-sharp/gstreamer-sharp,gstreamer-sharp/gstreamer-sharp,gstreamer-sharp/gstreamer-sharp,Forage/gstreamer-sharp,Forage/gstreamer-sharp,GStreamer/gstreamer-sharp,freedesktop-unofficial-mirror/gstreamer__gstreamer-sharp,Forage/gstreamer-sharp,GStreamer/gstreamer-sharp,freedesktop-unofficial-mirror/gstreamer__gstreamer-sharp