GPS: use the new nav_setting in a couple of the sample sketches

libraries/AP_GPS/examples/GPS_AUTO_test/GPS_AUTO_test.pde

@@ -44,7 +44,7 @@ void setup()
 
     Serial.println("GPS AUTO library test");
     gps = &GPS;
-    gps->init();
+    gps->init(GPS::GPS_ENGINE_AIRBORNE_2G);
 }
 
 void loop()

libraries/AP_GPS/examples/GPS_UBLOX_test/GPS_UBLOX_test.pde

@@ -26,7 +26,7 @@ void setup()
     gps.print_errors = true;
 
     Serial.println("GPS UBLOX library test");
-    gps.init();	 // GPS Initialization
+    gps.init(GPS::GPS_ENGINE_AIRBORNE_2G);	 // GPS Initialization
     delay(1000);
 }
 void loop()