Add option for custom mavlink configuration

This commit enables a option for users to add a custom mavlink configuration through rc.mavlink_override

ROMFS/px4fmu_common/init.d-posix/rcS

@@ -238,24 +238,30 @@ fi
 #
 . ${R}etc/init.d/rc.vehicle_setup
 
-# GCS link
-mavlink start -x -u $udp_gcs_port_local -r 4000000
-mavlink stream -r 50 -s POSITION_TARGET_LOCAL_NED -u $udp_gcs_port_local
-mavlink stream -r 50 -s LOCAL_POSITION_NED -u $udp_gcs_port_local
-mavlink stream -r 50 -s GLOBAL_POSITION_INT -u $udp_gcs_port_local
-mavlink stream -r 50 -s ATTITUDE -u $udp_gcs_port_local
-mavlink stream -r 50 -s ATTITUDE_QUATERNION -u $udp_gcs_port_local
-mavlink stream -r 50 -s ATTITUDE_TARGET -u $udp_gcs_port_local
-mavlink stream -r 50 -s SERVO_OUTPUT_RAW_0 -u $udp_gcs_port_local
-mavlink stream -r 20 -s RC_CHANNELS -u $udp_gcs_port_local
-mavlink stream -r 10 -s OPTICAL_FLOW_RAD -u $udp_gcs_port_local
-
-# API/Offboard link
-mavlink start -x -u $udp_offboard_port_local -r 4000000 -m onboard -o $udp_offboard_port_remote
-
-# Onboard link to camera
-mavlink start -x -u $udp_onboard_payload_port_local -r 4000 -f -m onboard -o $udp_onboard_payload_port_remote
+if [ -e etc/init.d-posix/rc.mavlink_override ]
+then
+	echo "Running non-default mavlink config rc.mavlink_override"
+	sh etc/init.d-posix/rc.mavlink_override
+else
+	# GCS link
+	mavlink start -x -u $udp_gcs_port_local -r 4000000
+	mavlink stream -r 50 -s POSITION_TARGET_LOCAL_NED -u $udp_gcs_port_local
+	mavlink stream -r 50 -s LOCAL_POSITION_NED -u $udp_gcs_port_local
+	mavlink stream -r 50 -s GLOBAL_POSITION_INT -u $udp_gcs_port_local
+	mavlink stream -r 50 -s ATTITUDE -u $udp_gcs_port_local
+	mavlink stream -r 50 -s ATTITUDE_QUATERNION -u $udp_gcs_port_local
+	mavlink stream -r 50 -s ATTITUDE_TARGET -u $udp_gcs_port_local
+	mavlink stream -r 50 -s SERVO_OUTPUT_RAW_0 -u $udp_gcs_port_local
+	mavlink stream -r 20 -s RC_CHANNELS -u $udp_gcs_port_local
+	mavlink stream -r 10 -s OPTICAL_FLOW_RAD -u $udp_gcs_port_local
+
+	# API/Offboard link
+	mavlink start -x -u $udp_offboard_port_local -r 4000000 -m onboard -o $udp_offboard_port_remote
+
+	# Onboard link to camera
+	mavlink start -x -u $udp_onboard_payload_port_local -r 4000 -f -m onboard -o $udp_onboard_payload_port_remote
 
+fi
 # execute autostart post script if any
 [ -e "$autostart_file".post ] && . "$autostart_file".post