matroska: Check the return value of gst_segment_do_seek()
matroska: Check the return value of gst_segment_do_seek()

gst_segment_do_seek() can fail.

pexip/gst-plugins-good,pexip/gst-plugins-good,GStreamer/gst-plugins-good,GStreamer/gst-plugins-good,GStreamer/gst-plugins-good,pexip/gst-plugins-good,pexip/gst-plugins-good,GStreamer/gst-plugins-good,pexip/gst-plugins-good