ardupilotmega.xml: report active EKF source sets and lanes

Author: landswellsong

message_definitions/v1.0/ardupilotmega.xml

@@ -1723,6 +1723,8 @@
       <field type="float" name="terrain_alt_variance">Terrain Altitude variance.</field>
       <extensions/>
       <field type="float" name="airspeed_variance">Airspeed variance.</field>
+      <field type="uint8_t" name="active_srcset_id" minValue="1" maxValue="3">Currently active source set.</field>
+      <field type="uint8_t" name="active_lane_id" minValue="1" maxValue="6">Currently estimator lane (core).</field>
     </message>
     <!-- realtime PID tuning message -->
     <message id="194" name="PID_TUNING">