gst/: Don't queue buffers in basesink when we are flushing.

gst/: Don't queue buffers in basesink when we are flushing.

Original commit message from CVS:
* gst/base/gstbasesink.c: (gst_basesink_finish_preroll),
(gst_basesink_chain_unlocked), (gst_basesink_activate):
* gst/gstminiobject.c: (gst_mini_object_get_type),
(gst_mini_object_free):
* gst/gstpad.c: (gst_pad_accept_caps), (gst_pad_query),
(gst_pad_push), (gst_pad_push_event):
* gst/gstqueue.c: (gst_queue_change_state):
Don't queue buffers in basesink when we are flushing.
Unref buffer when flushing in basesink.
Flush queue when going to READY
Unref buffer when _push() returns an error.
Don't free MiniObject instance when refcount is incremented
in _finalize() so that we can recover objects.