* decl.c (struct binding_level): New field using_directives.
	(push_using_decl): Not sorry anymore.
	(push_using_directive): New function.
	(lookup_tag): Use CP_DECL_CONTEXT to iterate.
	(unqualified_namespace_lookup): New function, code from ...
	(lookup_name_real): ... here.
	* decl2.c (lookup_using_namespace): Pass using list instead of
	initial scope.
	(validate_nonmember_using_decl): New function.
	(do_nonmember_using_decl): New function.
	(do_toplevel_using_decl): Use them.
	(do_local_using_decl): New function.
	(do_using_directive): Support block-level directives.
	* parse.y (simple_stmt): Support using declarations and
	directives.
	(namespace_qualifier, namespace_using_decl): New non-terminals.

From-SVN: r21089