PID: remove unnecessary includes from example

libraries/PID/examples/pid/pid.cpp

@@ -4,17 +4,8 @@
  */
 
 #include <AP_HAL/AP_HAL.h>
-#include <AP_Common/AP_Common.h>
-#include <AP_Progmem/AP_Progmem.h>
-#include <AP_Param/AP_Param.h>
-#include <StorageManager/StorageManager.h>
-#include <AP_Math/AP_Math.h>
 #include <PID/PID.h> // ArduPilot Mega RC Library
 
-#include <AP_HAL_AVR/AP_HAL_AVR.h>
-#include <AP_HAL_SITL/AP_HAL_SITL.h>
-#include <AP_HAL_Empty/AP_HAL_Empty.h>
-
 const AP_HAL::HAL& hal = AP_HAL::get_HAL();
 
 long radio_in;