AC_PID: replace header guard with pragma once

libraries/AC_PID/AC_HELI_PID.h

@@ -1,11 +1,9 @@
 // -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+#pragma once
 
 /// @file	AC_HELI_PID.h
 /// @brief	Helicopter Specific Rate PID algorithm, with EEPROM-backed storage of constants.
 
-#ifndef __AC_HELI_PID_H__
-#define __AC_HELI_PID_H__
-
 #include <AP_Common/AP_Common.h>
 #include <AP_Param/AP_Param.h>
 #include <stdlib.h>
@@ -45,5 +43,3 @@ private:
     float           _last_requested_rate;       // Requested rate from last iteration, used to calculate rate change of requested rate
     
 };
-
-#endif // __AC_HELI_PID_H__

libraries/AC_PID/AC_P.h

@@ -1,11 +1,9 @@
 // -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+#pragma once
 
 /// @file	AC_PD.h
 /// @brief	Generic PID algorithm, with EEPROM-backed storage of constants.
 
-#ifndef __AC_P_H__
-#define __AC_P_H__
-
 #include <AP_Common/AP_Common.h>
 #include <AP_Param/AP_Param.h>
 #include <stdlib.h>
@@ -67,5 +65,3 @@ public:
 private:
     AP_Float        _kp;
 };
-
-#endif // __AC_P_H__

libraries/AC_PID/AC_PID.h

@@ -1,11 +1,9 @@
 // -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+#pragma once
 
 /// @file	AC_PID.h
 /// @brief	Generic PID algorithm, with EEPROM-backed storage of constants.
 
-#ifndef __AC_PID_H__
-#define __AC_PID_H__
-
 #include <AP_Common/AP_Common.h>
 #include <AP_Param/AP_Param.h>
 #include <stdlib.h>
@@ -106,5 +104,3 @@ protected:
 
     DataFlash_Class::PID_Info        _pid_info;
 };
-
-#endif // __AC_PID_H__

libraries/AC_PID/AC_PI_2D.h

@@ -1,11 +1,9 @@
 // -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+#pragma once
 
 /// @file	AC_PI_2D.h
 /// @brief	Generic PID algorithm, with EEPROM-backed storage of constants.
 
-#ifndef __AC_PI_2D_H__
-#define __AC_PI_2D_H__
-
 #include <AP_Common/AP_Common.h>
 #include <AP_Param/AP_Param.h>
 #include <stdlib.h>
@@ -94,5 +92,3 @@ protected:
     Vector2f        _input;         // last input for derivative
     float           _filt_alpha;    // input filter alpha
 };
-
-#endif // __AC_PI_2D_H__