re PR c++/81247 (ICE on invalid C++ code with malformed namespace declaration: in do_push_nested_namespace, at cp/name-lookup.c:6002)

	PR c++/81247
	* parser.c (cp_parser_namespace_definition): Immediately close the
	namespace if there's no open-brace.
	* name-lookup.c (do_pushdecl): Reset OLD when pushing into new
	namespace.

From-SVN: r249804