Compile-time improvement: 2/n.

Compile-time improvement: 2/n.

	* cp-tree.h (struct cxx_binding): New datatype;
	(struct lang_identifier): Use it.
	(LOCAL_BINDING_P): Adjust definition.
	(INHERITED_VALUE_BINDING_P): Likewise.
	(BINDING_SCOPE): Likewise.
	(BINDING_HAS_LEVEL_P): Likewise.
	(BINDING_VALUE): Likewise.
	(BINDING_TYPE): Likewise.
	(IDENTIFIER_VALUE): Likewise.
	(struct tree_binding): Remove.
	(TS_CP_BINDING): Likewise.
	((union lang_tree_node): Remove field "binding".
	(cxx_binding_clear): New macro.
	(binding_for_name): Adjust return type.
	(qualified_lookup_using_namespace): Adjust prototype.
	(lookup_using_namespace): Adjust prototype.
	(cxx_scope_find_binding_for_name): Declare.
	* cp-tree.def: Remove CPLUS_BINDING definition.
	* parse.y (parse_scoped_id): Don't type-abuse of 'id'.  Allocate
	temporary cxx_binding on stack.  Simplify.
	* decl.c (push_binding): Adjust local variable type.
	(add_binding): Likewise.
	(push_class_binding): Likewise.
	(pop_binding): Likewise.
	(poplevel): Likewise.
	(poplevel_class): Likewise.
	(free_bindings):  Adjust type.
	(find_binding): Adjust return type, add a third parameter. Remove
	non-useful assertion now that we use static typing.
	(cxx_scope_find_binding_for_name): New function.
	(binding_for_name): Use it.  Adjust local variable type. Simplify.
	(namespace_binding):  Simplify.
	(set_namespace_binding): Likewise.
	(set_identifier_type_value_with_scope): Adjust local variable type.
	(lookup_tag): Don't type-abuse of local variable 'old'.
	(lookup_namespace_name): Likewise.  Allocate binding on stack.
	(select_decl): Adjust prototype.
	(unqualified_namespace_lookup):  Allocate binding on stack.
	Don't type-abuse of local variable 'val'.
	(lookup_name_real): Likewise.
	(maybe_inject_for_scope_var): Adjust local variable type.
	(cp_tree_node_structure): Remove CPLUS_BINDING case label.
	(namespace_binding): Adjust logic, simplify.
	(BINDING_LEVEL): Adjust definition.
	(push_class_level_binding): Adjust local variable type.
	(struct cxx_saved_binding): Adjust field 'binding' type.
	* decl2.c (ambiguous_decl): Adjust prototype.
	(lookup_using_namespace): Adjust local variable type.
	(qualified_lookup_using_namespace): Catch type error and correct
	ensueing logic error.
	(do_nonmember_using_decl): Adjust local variable type.  Allocate
	temporary cxx_binding on stack.
	(do_toplevel_using_decl): Adjust local variable type.
	* ptree.c (cxx_print_cxx_binding): New function.
	(cxx_print_identifier): Use it.
	(cxx_print_xnode): Delete CPLUS_BINDING case label.

From-SVN: r64405