gst/flv/gstflvdemux.c: Don't post an error message on the bus if sending EOS downstre...

gst/flv/gstflvdemux.c: Don't post an error message on the bus if sending EOS downstream didn't work. Fixes bug #550454.

Original commit message from CVS:
* gst/flv/gstflvdemux.c: (gst_flv_demux_loop),
(gst_flv_demux_find_offset), (gst_flv_demux_handle_seek_push),
(gst_flv_demux_handle_seek_pull):
Don't post an error message on the bus if sending EOS downstream
didn't work. Fixes bug #550454.
Fix seek event handling to look at the flags of the seek event
instead of assuming some random flags, don't send segment-start
messages when operating in push mode and push seek events upstream
if we couldn't handle them.