Original commit message from CVS:

* check/elements/matroskamux.c: (setup_src_pad), (setup_sink_pad),
(setup_matroskamux), (check_buffer_data), (GST_START_TEST):
* gst/matroska/matroska-mux.c: (gst_matroska_mux_finalize),
(gst_matroska_mux_reset), (gst_matroska_mux_audio_pad_setcaps),
(gst_matroska_mux_start), (gst_matroska_mux_write_data),
(gst_matroska_mux_collected):
Fix leaks and invalid memory access as reported by valgrind