Fixed some sitl init bugs.

src/modules/sensors/sensors.cpp

@@ -1250,7 +1250,7 @@ Sensors::vehicle_control_mode_poll()
 void
 Sensors::parameter_update_poll(bool forced)
 {
-	bool param_updated;
+	bool param_updated=false;
 
 	/* Check if any parameter has changed */
 	orb_check(_params_sub, &param_updated);

src/modules/simulator/simulator_mavlink.cpp

@@ -463,10 +463,12 @@ void Simulator::pollForMAVLinkMessages(bool publish)
 	char serial_buf[1024];
 
 	struct pollfd fds[2];
+	memset(fds, 0, sizeof(fds));
 	unsigned fd_count = 1;
 	fds[0].fd = _fd;
 	fds[0].events = POLLIN;
 
+
 	if (serial_fd >= 0) {
 		fds[1].fd = serial_fd;
 		fds[1].events = POLLIN;