ext/faad/gstfaad.*: Do some timestamp smoothing (matroskademux apparently sends multiple buffers in a row with the sa...

Original commit message from CVS:
* ext/faad/gstfaad.c: (gst_faad_base_init), (gst_faad_class_init),
(gst_faad_init), (gst_faad_srcgetcaps), (gst_faad_event),
(gst_faad_chain), (gst_faad_change_state):
* ext/faad/gstfaad.h:
Do some timestamp smoothing (matroskademux apparently sends
multiple buffers in a row with the same timestamp); fix
duration on outgoing buffers; fix change state function; use
GST_DEBUG_FUNCPTR for pad functions.