@brief Wait for events on a single GPIO line. @param device Name, path, number or label of the gpiochip. @param event_type Type of events to listen for. @param offset GPIO line offset to monitor. @param active_low The active state of this line - true if low. @param consumer Name of the consumer. @param timeout Maximum wait time for each iteration. @param poll_cb Callback function to call when waiting for events. @param event_cb Callback function to call for each line event. @param data User data passed to the callback. @param flags The flags for the line. @return 0 if no errors were encountered, -1 if an error occurred. @note The way the ctxless event loop works is described in detail in ::gpiod_ctxless_event_monitor_multiple - this is just a wrapper aound this routine which calls it for a single GPIO line.