* cp-tree.h (DECL_NAMESPACE_ALIAS, ORIGINAL_NAMESPACE): Declare.
	* decl.c (lookup_name_real): Add namespaces_only parameter.
	If set, return only NAMESPACE_DECLs.
	(select_decl): Likewise.
	(identifier_type_value): Give additional parameter.
	(lookup_name_nonclass): Likewise.
	(lookup_name): Likewise.
	(find_binding): Skip namespace aliases.
	(binding_for_name): Likewise.
	(push_namespace): Check for namespace aliases.
	(lookup_name_namespace_only): New function.
	(begin_only_namespace_names, end_only_namespace_names): New functions.
	* decl2.c (set_decl_namespace): Skip namespace aliases.
	(do_using_directive): Likewise.
	(do_namespace_alias): Produce namespace aliases, fix alias
	redeclaration.
	* error.c (dump_decl): Support SCOPE_REF.
	* parse.y (extdef): Wrap lookup with namespace_only for namespace
	aliases and using declarations.

From-SVN: r20236