PR c++/56840
	* pt.c (check_specialization_namespace): Allow any enclosing
	namespace.
	(check_unqualified_spec_or_inst): New.
	(check_explicit_specialization): Call it.
	* parser.c (cp_parser_elaborated_type_specifier)
	(cp_parser_class_head): Call it.

From-SVN: r242348