AP_NavEKF: Add GPS glitching monitor to EKF status report

libraries/AP_NavEKF/AP_NavEKF.cpp

@@ -4972,6 +4972,7 @@ void  NavEKF::getFilterStatus(nav_filter_status &status) const
     status.flags.takeoff = expectGndEffectTakeoff; // The EKF has been told to expect takeoff and is in a ground effect mitigation mode
     status.flags.touchdown = expectGndEffectTouchdown; // The EKF has been told to detect touchdown and is in a ground effect mitigation mode
     status.flags.using_gps = (imuSampleTime_ms - lastPosPassTime) < 4000;
+    status.flags.gps_glitching = !gpsAccuracyGood; // The GPS is glitching
 }
 
 // send an EKF_STATUS message to GCS

libraries/AP_NavEKF/AP_Nav_Common.h

@@ -35,6 +35,7 @@ union nav_filter_status {
         uint16_t takeoff            : 1; // 11 - true if filter is compensating for baro errors during takeoff
         uint16_t touchdown          : 1; // 12 - true if filter is compensating for baro errors during touchdown
         uint16_t using_gps          : 1; // 13 - true if we are using GPS position
+        uint16_t gps_glitching      : 1; // 14 - true if the the GPS is glitching
     } flags;
     uint16_t value;
 };