examples/seeking/seek.c: Updated seek example.

examples/seeking/seek.c: Updated seek example.

Original commit message from CVS:
* examples/seeking/seek.c: (make_vorbis_theora_pipeline),
(query_rates), (query_positions_elems), (query_positions_pads),
(do_seek), (seek_cb), (stop_seek):
Updated seek example.

* gst/playback/gstdecodebin.c: (remove_element_chain), (unlinked):
* gst/playback/gstplaybasebin.c: (queue_threshold_reached),
(queue_out_of_data), (gen_preroll_element), (new_decoded_pad):
* gst/playback/gstplaybin.c: (add_sink):
* gst/playback/gststreaminfo.c: (gst_stream_info_dispose),
(gst_stream_info_set_mute):
Some refcount leak fixes.