(objc_send_load): New function.

(objc_class_tree): New structure.
(create_tree_of_subclasses_inherited_from): New function.
(__objc_tree_insert_class): New function.
(objc_tree_insert_class): New function.
(objc_preorder_traverse): New function.
(objc_postorder_traverse): New function.
(__objc_tree_print): New function.
(__objc_destroy_class_tree_node): New function.
(class_is_subclass_of_class): New function.
(__objc_exec_class): Allocate class tree list and load hash table.
(__objc_send_message_in_list): Rewrite using hash table.
(__objc_send_load): Remove calls to _objc_load_callback.
(objc_send_load): Make static.  Create Tree of classes resembling
class hierarchy for all modules.  Call __objc_send_load on all of
the modules in __objc_module_list.
(__objc_create_classes_tree): New function.

From-SVN: r14304