swaybar: reset tokener if json is incomplete

If the tokener parses incomplete json, it sets its error value to
json_tokener_continue. This means that extra json should be provided,
but the code was providing the entire object again. In the interest of
simplicity, the tokener is reset so that buffer_pos always points to the
start of the current object.

swaybar/i3bar.c

@@ -199,6 +199,7 @@ bool i3bar_handle_readable(struct status_line *status) {
 				}
 				buffer_pos = status->buffer_index = 0;
 			} else if (json_tokener_get_error(status->tokener) == json_tokener_continue) {
+				json_tokener_reset(status->tokener);
 				if (status->buffer_index < status->buffer_size) {
 					// move the object to the start of the buffer
 					status->buffer_index -= buffer_pos;