Plane: init terrain to locaiton and wpnav sub sytems

ArduPlane/quadplane.cpp

@@ -789,6 +789,9 @@ bool QuadPlane::setup(void)
         AP_BoardConfig::config_error("Unable to allocate %s", "wp_nav");
     }
     AP_Param::load_object_from_eeprom(wp_nav, wp_nav->var_info);
+#if AP_TERRAIN_AVAILABLE
+    wp_nav->set_terrain(&plane.terrain);
+#endif
 
     loiter_nav = new AC_Loiter(inertial_nav, *ahrs_view, *pos_control, *attitude_control);
     if (!loiter_nav) {

ArduPlane/system.cpp

@@ -162,6 +162,11 @@ void Plane::init_ardupilot()
 #if AC_FENCE == ENABLED
     fence.init();
 #endif
+
+#if AP_TERRAIN_AVAILABLE
+    Location::set_terrain(&terrain);
+#endif
+
 }
 
 //********************************************************************************