Fixed long standing mem-leak

Fixed long standing mem-leak

Original commit message from CVS:
* gst/gstelement.c: (gst_element_class_init),
(gst_element_set_state), (activate_pads),
(gst_element_save_thyself):
* tools/gst-compprep.c: (main):
* tools/gst-inspect.c: (print_element_properties_info):
* tools/gst-xmlinspect.c: (print_element_properties):
Fixed long standing mem-leak