logger: fix -e parameter (logger immediately stopped again after start)

src/modules/logger/logger.cpp

@@ -533,7 +533,8 @@ void Logger::run()
 			bool armed = (vehicle_status_sub.get().arming_state == vehicle_status_s::ARMING_STATE_ARMED) ||
 				     (vehicle_status_sub.get().arming_state == vehicle_status_s::ARMING_STATE_ARMED_ERROR);
 
-			if (_enabled != armed && !_log_until_shutdown) {
+			if (_was_armed != armed && !_log_until_shutdown) {
+				_was_armed = armed;
 				if (armed) {
 					start_log();
 

src/modules/logger/logger.h

@@ -157,6 +157,7 @@ private:
 	char 						_log_dir[64];
 	bool						_has_log_dir = false;
 	bool						_enabled = false;
+	bool						_was_armed = false;
 
 	// statistics
 	hrt_abstime					_start_time; ///< Time when logging started (not the logger thread)