AP_LandingGear: make and use AP_LANDINGGEAR_ENABLED

libraries/AP_LandingGear/AP_LandingGear.cpp

@@ -1,4 +1,7 @@
 #include "AP_LandingGear.h"
+
+#if AP_LANDINGGEAR_ENABLED
+
 #include <AP_Relay/AP_Relay.h>
 #include <AP_Math/AP_Math.h>
 #include <SRV_Channel/SRV_Channel.h>
@@ -10,6 +13,10 @@
 #include <SITL/SITL.h>
 #endif
 
+#if defined(APM_BUILD_TYPE)
+//  - this is just here to encourage the build system to supply the "legacy build defines".  The actual dependecy is in the AP_LandingGear.h and AP_LandingGear_config.h headers
+#endif
+
 extern const AP_HAL::HAL& hal;
 
 const AP_Param::GroupInfo AP_LandingGear::var_info[] = {
@@ -331,3 +338,5 @@ void AP_LandingGear::deploy_for_landing()
         deploy();
     }
 }
+
+#endif

libraries/AP_LandingGear/AP_LandingGear.h

@@ -2,6 +2,10 @@
 /// @brief  Landing gear control library
 #pragma once
 
+#include "AP_LandingGear_config.h"
+
+#if AP_LANDINGGEAR_ENABLED
+
 #include <AP_Param/AP_Param.h>
 #include <AP_Common/AP_Common.h>
 
@@ -123,3 +127,5 @@ private:
 
     static AP_LandingGear *_singleton;
 };
+
+#endif  // AP_LANDINGGEAR_ENABLED

libraries/AP_LandingGear/AP_LandingGear_config.h

@@ -0,0 +1,10 @@
+#pragma once
+
+#include <AP_Vehicle/AP_Vehicle_Type.h>
+#include <AP_HAL/AP_HAL_Boards.h>
+
+// historical compatability; only Copters get it - and Plane on
+// non-minimized boards.
+#ifndef AP_LANDINGGEAR_ENABLED
+#define AP_LANDINGGEAR_ENABLED (APM_BUILD_COPTER_OR_HELI || (!HAL_MINIMIZE_FEATURES && APM_BUILD_TYPE(APM_BUILD_ArduPlane)))
+#endif