gst/mpegstream/gstmpegdemux.c: Add pad to element *after* setting functions such...

gst/mpegstream/gstmpegdemux.c: Add pad to element *after* setting functions such as event handler.

Original commit message from CVS:
2004-01-05  Ronald Bultje  <rbultje@ronald.bitfreak.net>

* gst/mpegstream/gstmpegdemux.c: (gst_mpeg_demux_parse_syshead):
Add pad to element *after* setting functions such as event handler.
Without this, the scheduler (opt) will link pads, set the event
handler from the default event function (dispatcher in gstpad.c)
and *after* that, we will set our own event function, which will
thus never be used (and thus mpegdemux doesn't handle events).