cp-tree.h (struct lang_type_class): add field for key method

        * cp-tree.h (struct lang_type_class): add field for key method
        (cp_global_trees): rename dynamic_classes to keyed_classes
        (key_method): add definition
        * class.c (finish_struct_1): compute class's key method, and add
        the class to keyed_classes list if there is no key method.
        * decl.c (finish_function): add class to keyed_classes list if we
        see a definition of the class's key method.
        * pt.c (instantiate_class_template): add template specialization
        of a dynamic class to keyed_classes list.
        * decl2.c (key_method): remove
        (finish_file): iterate only through keyed_classes list when
        deciding whether to emit vtables, remove class from its list after
        we do the emission.

From-SVN: r60850