AC_WPNav: make more member pointers const

libraries/AC_WPNav/AC_WPNav.cpp

@@ -68,7 +68,7 @@ const AP_Param::GroupInfo AC_WPNav::var_info[] PROGMEM = {
 // Note that the Vector/Matrix constructors already implicitly zero
 // their values.
 //
-AC_WPNav::AC_WPNav(const AP_InertialNav* inav, AP_AHRS* ahrs, APM_PI* pid_pos_lat, APM_PI* pid_pos_lon, AC_PID* pid_rate_lat, AC_PID* pid_rate_lon) :
+AC_WPNav::AC_WPNav(const AP_InertialNav* inav, const AP_AHRS* ahrs, APM_PI* pid_pos_lat, APM_PI* pid_pos_lon, AC_PID* pid_rate_lat, AC_PID* pid_rate_lon) :
     _inav(inav),
     _ahrs(ahrs),
     _pid_pos_lat(pid_pos_lat),

libraries/AC_WPNav/AC_WPNav.h

@@ -40,7 +40,7 @@ class AC_WPNav
 public:
 
     /// Constructor
-    AC_WPNav(const AP_InertialNav* inav, AP_AHRS* ahrs, APM_PI* pid_pos_lat, APM_PI* pid_pos_lon, AC_PID* pid_rate_lat, AC_PID* pid_rate_lon);
+    AC_WPNav(const AP_InertialNav* inav, const AP_AHRS* ahrs, APM_PI* pid_pos_lat, APM_PI* pid_pos_lon, AC_PID* pid_rate_lat, AC_PID* pid_rate_lon);
 
     ///
     /// simple loiter controller
@@ -185,13 +185,13 @@ protected:
 
     // references to inertial nav and ahrs libraries
     const AP_InertialNav* const _inav;
-    AP_AHRS*        _ahrs;
+    const AP_AHRS*        const _ahrs;
 
     // pointers to pid controllers
-    APM_PI*		_pid_pos_lat;
-    APM_PI*		_pid_pos_lon;
-    AC_PID*		_pid_rate_lat;
-    AC_PID*		_pid_rate_lon;
+    APM_PI*		const _pid_pos_lat;
+    APM_PI*		const _pid_pos_lon;
+    AC_PID*		const _pid_rate_lat;
+    AC_PID*		const _pid_rate_lon;
 
     // parameters
     AP_Float    _loiter_speed_cms;      // maximum horizontal speed in cm/s while in loiter