Copy seqnums from events to messages so that they can all be related back to eachother.

Copy seqnums from events to messages so that they can all be related back to eachother.

Original commit message from CVS:
* gst/gstbin.c: (bin_handle_async_start),
(gst_bin_handle_message_func), (gst_bin_query):
* libs/gst/base/gstbasesink.c: (gst_base_sink_render_object),
(gst_base_sink_event), (gst_base_sink_change_state):
* libs/gst/base/gstbasesrc.c: (gst_base_src_perform_seek),
(gst_base_src_loop), (gst_base_src_change_state):
Copy seqnums from events to messages so that they can all be related
back to eachother.