* target.c, target.h (target_read_string): Provide error detection to

	* target.c, target.h (target_read_string): Provide error detection to
	caller.  Put string in malloc'd space, so caller need not impose
	arbitrary limits.
	* solib.c (find_solib): Update to use new interface.
	* irix5-nat.c (find_solib): Read o_path from inferior
	(clear_solib): Free storage for o_path.
	* valprint.c (val_print_string): Add comments.