gst/base/gstcollectpads.c: Broadcast the condition when shutting down, to make sure we wake all threads up. Shut down...

Original commit message from CVS:
* gst/base/gstcollectpads.c: (gst_collectpads_finalize),
(gst_collectpads_stop):
Broadcast the condition when shutting down, to make sure we wake all
threads up. Shut down pads on finalize, for safety.