processorTrackerGnss fixes frame O if only SensorGnss

src/processor/processor_tracker_gnss.cpp

@@ -539,7 +539,9 @@ void ProcessorTrackerGnss::resetDerived()
 
 void ProcessorTrackerGnss::postProcess()
 {
-
+    // Fix orientation of last frame if no other processors
+    if (getSensor()->getHardware()->getSensorList().size() == 1)
+        getProblem()->getLastFrame()->getO()->fix();
 }
 
 void ProcessorTrackerGnss::removeOutliers(FactorBasePtrList fac_list, CaptureBasePtr cap)