* stabsread.c (read_one_struct_field): Don't give up on unknown

	* stabsread.c (read_one_struct_field): Don't give up on unknown
	visibility character, just shove it in fip->list->visibility.
	(read_baseclasses): Don't give up on unknown virtual or visibility
	characters, just assume a reasonable default, complain, and keep
	going.
	(attach_fields_to_type): Complain on unrecognized visibility.
	One result of all this is that '9' (VISIBILITY_IGNORE) can be used
	in a stab as well as being something which GDB uses internally.