check/gst/gstbin.c: Change for new bus API.

check/gst/gstbin.c: Change for new bus API.

Original commit message from CVS:
* check/gst/gstbin.c: (GST_START_TEST):
Change for new bus API.

* check/gst/gstbus.c: (message_func_eos), (message_func_app),
(send_messages), (GST_START_TEST), (gstbus_suite):
Change for new bus signal API.

* gst/gstbus.c: (gst_bus_class_init), (gst_bus_have_pending),
(gst_bus_source_prepare), (gst_bus_source_check),
(gst_bus_create_watch), (gst_bus_add_watch_full),
(gst_bus_add_watch), (gst_bus_poll), (gst_bus_async_signal_func),
(gst_bus_sync_signal_handler), (gst_bus_add_signal_watch):
* gst/gstbus.h:
Remove support for multiple GSources operating on different
message types as it is too complex and unneeded when using
signals.
Added support for receiving signals from the bus.