AP_HAL_SITL: guard against DSP being compiled out of code

libraries/AP_HAL_SITL/DSP.cpp

@@ -17,6 +17,8 @@
 
 #include <AP_HAL/AP_HAL.h>
 
+#if HAL_WITH_DSP
+
 #include "AP_HAL_SITL.h"
 #include <AP_Math/AP_Math.h>
 #include <GCS_MAVLink/GCS.h>
@@ -209,3 +211,5 @@ void DSP::calculate_fft(complexf *samples, uint16_t fftlen)
         istep <<= 1;
     }
 }
+
+#endif

libraries/AP_HAL_SITL/DSP.h

@@ -17,6 +17,9 @@
 #pragma once
 
 #include <AP_HAL/AP_HAL.h>
+
+#if HAL_WITH_DSP
+
 #include "AP_HAL_SITL.h"
 
 #include <complex>
@@ -55,3 +58,5 @@ private:
     void vector_add_float(const float* vin1, const float* vin2, float* vout, uint16_t len) const override;
     void calculate_fft(complexf* f, uint16_t length);
 };
+
+#endif

libraries/AP_HAL_SITL/HAL_SITL_Class.cpp

@@ -46,7 +46,9 @@ static Empty::RCInput  sitlRCInput;
 static RCOutput sitlRCOutput(&sitlState);
 static GPIO sitlGPIO(&sitlState);
 static AnalogIn sitlAnalogIn(&sitlState);
+#if HAL_WITH_DSP
 static DSP dspDriver;
+#endif
 
 
 // use the Empty HAL for hardware we don't emulate
@@ -104,7 +106,9 @@ HAL_SITL::HAL_SITL() :
         &utilInstance,      /* util */
         &emptyOpticalFlow,  /* onboard optical flow */
         &emptyFlash,        /* flash driver */
+#if HAL_WITH_DSP
         &dspDriver,         /* dsp driver */
+#endif
 #if HAL_NUM_CAN_IFACES
         (AP_HAL::CANIface**)canDrivers
 #else