ext/mpeg2dec/gstmpeg2dec.c: Don't send things to NULL PAD_PEERs

ext/mpeg2dec/gstmpeg2dec.c: Don't send things to NULL PAD_PEERs

Original commit message from CVS:
* ext/mpeg2dec/gstmpeg2dec.c:
Don't send things to NULL PAD_PEERs

* gst/deinterlace/gstdeinterlace.c: (gst_deinterlace_chain):
Copy-on-write the incoming buffer.

* gst/mpegstream/gstdvddemux.h:
* gst/mpegstream/gstmpegclock.h:
* gst/mpegstream/gstmpegdemux.c: (gst_mpeg_demux_parse_syshead),
(normal_seek), (gst_mpeg_demux_handle_src_event):
* gst/mpegstream/gstmpegdemux.h:
* gst/mpegstream/gstmpegpacketize.h:
* gst/mpegstream/gstmpegparse.c:
(gst_mpeg_parse_update_streaminfo), (gst_mpeg_parse_reset),
(gst_mpeg_parse_handle_discont), (gst_mpeg_parse_parse_packhead),
(gst_mpeg_parse_loop), (gst_mpeg_parse_get_rate),
(gst_mpeg_parse_convert_src), (gst_mpeg_parse_handle_src_query),
(gst_mpeg_parse_handle_src_event), (gst_mpeg_parse_change_state):
* gst/mpegstream/gstmpegparse.h:
* gst/mpegstream/gstrfc2250enc.h:
Various changes to the way time is computed that make seeking and
total time estimation much better here.
Use G_BEGIN/END_DECLS instead of __cplusplus

* gst/videocrop/gstvideocrop.c: (gst_video_crop_chain):
Use gst_buffer_stamp instead of only copying the TIMESTAMP