CopterMotors: fix example sketch

libraries/AP_Motors/examples/AP_Motors_test/AP_Motors_test.pde

@@ -6,15 +6,18 @@
 // Libraries
 #include <AP_Common.h>
 #include <AP_Progmem.h>
-#include <AP_HAL.h>
 #include <AP_Param.h>
+#include <AP_HAL.h>
+#include <AP_HAL_AVR.h>
+#include <AP_HAL_PX4.h>
+#include <AP_HAL_Linux.h>
+#include <AP_HAL_Empty.h>
 #include <AP_Math.h>        // ArduPilot Mega Vector/Matrix math Library
 #include <RC_Channel.h>     // RC Channel Library
 #include <AP_Motors.h>
 #include <AP_Curve.h>
 #include <AP_Notify.h>
 
-#include <AP_HAL_AVR.h>
 const AP_HAL::HAL& hal = AP_HAL_BOARD_DRIVER;
 
 RC_Channel rc1(0), rc2(1), rc3(2), rc4(3);