AP_DAL: fixed build without VisualOdometry

libraries/AP_DAL/AP_DAL.cpp

@@ -74,7 +74,9 @@ void AP_DAL::start_frame(AP_DAL::FrameType frametype)
     _airspeed.start_frame();
     _rangefinder.start_frame();
     _beacon.start_frame();
+#if HAL_VISUALODOM_ENABLED
     _visualodom.start_frame();
+#endif
 
     // populate some derivative values:
     _micros = _RFRH.time_us;

libraries/AP_DAL/AP_DAL.h

@@ -139,9 +139,11 @@ public:
     AP_DAL_Beacon *beacon() {
         return _beacon.beacon();
     }
+#if HAL_VISUALODOM_ENABLED
     AP_DAL_VisualOdom *visualodom() {
         return _visualodom.visualodom();
     }
+#endif
 
     // this method *always* returns you the compass.  This is in
     // constrast to get_compass, which only returns the compass once
@@ -260,7 +262,9 @@ public:
         _beacon.handle_message(msg);
     }
     void handle_message(const log_RVOH &msg) {
+#if HAL_VISUALODOM_ENABLED
         _visualodom.handle_message(msg);
+#endif
     }
 #endif
 
@@ -295,7 +299,9 @@ private:
     AP_DAL_Compass _compass;
     AP_DAL_Airspeed _airspeed;
     AP_DAL_Beacon _beacon;
+#if HAL_VISUALODOM_ENABLED
     AP_DAL_VisualOdom _visualodom;
+#endif
 
     static bool logging_started;
     static bool force_write;

libraries/AP_DAL/AP_DAL_VisualOdom.cpp

@@ -2,6 +2,8 @@
 
 #include <AP_VisualOdom/AP_VisualOdom.h>
 
+#if HAL_VISUALODOM_ENABLED
+
 #include <AP_Logger/AP_Logger.h>
 #include "AP_DAL.h"
 
@@ -21,3 +23,5 @@ void AP_DAL_VisualOdom::start_frame()
 
     WRITE_REPLAY_BLOCK_IFCHANGD(RVOH, RVOH, old);
 }
+
+#endif // HAL_VISUALODOM_ENABLED

libraries/AP_DAL/AP_DAL_VisualOdom.h

@@ -6,6 +6,8 @@
 
 #include <AP_Vehicle/AP_Vehicle_Type.h>
 
+#if HAL_VISUALODOM_ENABLED
+
 class AP_DAL_VisualOdom {
 public:
 
@@ -49,3 +51,5 @@ private:
 
     struct log_RVOH RVOH;
 };
+
+#endif // HAL_VISUALODOM_ENABLED