AP_Vehicle: move SITL object up to AP_Vehicle

libraries/AP_Vehicle/AP_Vehicle.h

@@ -46,6 +46,9 @@
 #include <AP_Frsky_Telem/AP_Frsky_Parameters.h>
 #include <AP_ExternalAHRS/AP_ExternalAHRS.h>
 #include <AP_VideoTX/AP_SmartAudio.h>
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
+#include <SITL/SITL.h>
+#endif
 
 class AP_Vehicle : public AP_HAL::HAL::Callbacks {
 
@@ -363,6 +366,10 @@ protected:
 
     ModeReason control_mode_reason = ModeReason::UNKNOWN;
 
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
+    SITL::SIM sitl;
+#endif
+
 private:
 
     // delay() callback that processing MAVLink packets