gst/gstelement.c: Cleanup the error case.

gst/gstelement.c: Cleanup the error case.

Original commit message from CVS:
* gst/gstelement.c: (gst_element_set_locked_state),
(gst_element_dispose):
Cleanup the error case.
* gst/gstobject.c: (gst_object_dispose):
print a critical when some object was disposed with
a parent, also revive the object since it might
crash the parent.