ext/jpeg/gstjpegenc.c: fix DURATION on outgoing buffers

ext/jpeg/gstjpegenc.c: fix DURATION on outgoing buffers

Original commit message from CVS:
* ext/jpeg/gstjpegenc.c: (gst_jpegenc_get_type),
(gst_jpegenc_chain):
fix DURATION on outgoing buffers
* gst/asfdemux/gstasfdemux.c: (gst_asf_demux_handle_sink_event):
debug using time formats
* sys/ximage/ximagesink.c: (gst_ximagesink_xcontext_get):
* sys/xvimage/xvimagesink.c: (gst_xvimagesink_get_xv_support),
(gst_xvimagesink_sink_link):
windows with width/height 0 generate X errors, so don't allow them