AP_GPS: Add missing setup for GPS_AUTO_test

GPS_AUTO_test was missing some setup lines.

libraries/AP_GPS/examples/GPS_AUTO_test/GPS_AUTO_test.pde

@@ -37,6 +37,7 @@
 #include <AP_Rally.h>
 #include <AP_Scheduler.h>
 #include <AP_BattMonitor.h>
+#include <AP_SerialManager.h>
 
 const AP_HAL::HAL& hal = AP_HAL_BOARD_DRIVER;
 
@@ -45,6 +46,8 @@ AP_BoardLED board_led;
 
 AP_GPS gps;
 
+AP_SerialManager serial_manager;
+
 #define T6 1000000
 #define T7 10000000
 
@@ -54,6 +57,8 @@ void setup()
 
     // initialise the leds
     board_led.init();
+    serial_manager.init();
+    gps.init(NULL, serial_manager);
 }
 
 void loop()