libobs: Fix bug where outputs would not set stopped event

When an output fails to connect and it's already been prematurely
stopped, the event to mark the output as stopped would not be signaled,
causing obs_output_destroy to lock up indefinitely while waiting for the
event to be signaled.

libobs/obs-output.c

@@ -1819,6 +1819,7 @@ static void obs_output_end_data_capture_internal(obs_output_t *output,
 		if (signal) {
 			signal_stop(output);
 			output->stop_code = OBS_OUTPUT_SUCCESS;
+			os_event_signal(output->stopping_event);
 		}
 		return;
 	}