c++: correct object scope handling

The way cp_parser_lookup_name handles object scope (i.e. the scope on the
RHS of a . or -> expression) is a bit subtle: before the lookup it's in
parser->context->object type, and after the lookup it's in
parser->object_scope.  But a couple of places that elide lookups were
failing to do the same transform.

I'm not aware of this breaking anything currently.

gcc/cp/ChangeLog:

	* parser.c (cp_parser_template_name): Move object type.
	(cp_parser_pre_parsed_nested_name_specifier): Likewise.