qtdemux: free seqh after calling qtdemux_parse_svq3_stsd_data()

The seqh buffer allocated in qtdemux_parse_svq3_stsd_data() needs to
be freed by the caller after use.

https://bugzilla.gnome.org/show_bug.cgi?id=777157

Signed-off-by: Andre McCurdy <armccurdy@gmail.com>

gst/isomp4/qtdemux.c

@@ -10375,6 +10375,7 @@ qtdemux_parse_trak (GstQTDemux * qtdemux, GNode * trak)
              * than its own fourcc */
             gst_caps_set_simple (stream->caps, "seqh", GST_TYPE_BUFFER, seqh,
                 NULL);
+            gst_buffer_unref (seqh);
           }
 
           GST_DEBUG_OBJECT (qtdemux, "found codec_data in stsd");