Make all immobiles have no radar drift.

rts/Sim/Units/Unit.cpp

@@ -555,7 +555,7 @@ float3 CUnit::GetErrorVector(int argAllyTeam) const
 	const int atSightMask = losStatus[argAllyTeam];
 
 	const int isVisible = 2 * ((atSightMask & LOS_INLOS  ) != 0 ||                  teamHandler.Ally(argAllyTeam, allyteam)); // in LOS or allied, no error
-	const int seenGhost = 4 * ((atSightMask & LOS_PREVLOS) != 0 && gameSetup->ghostedBuildings && unitDef->IsBuildingUnit()); // seen ghosted building, no error
+	const int seenGhost = 4 * ((atSightMask & LOS_PREVLOS) != 0 && gameSetup->ghostedBuildings && unitDef->IsImmobileUnit()); // seen ghosted immobiles, no error
 	const int isOnRadar = 8 * ((atSightMask & LOS_INRADAR) != 0                                                            ); // current radar contact
 
 	float errorMult = 0.0f;