Sub: move dummy methods into system.cpp

ArduSub/GCS_Mavlink.cpp

@@ -836,7 +836,3 @@ int32_t GCS_MAVLINK_Sub::global_position_int_relative_alt() const {
     }
     return GCS_MAVLINK::global_position_int_relative_alt();
 }
-
-// dummy method to avoid linking AFS
-bool AP_AdvancedFailsafe::gcs_terminate(bool should_terminate, const char *reason) { return false; }
-AP_AdvancedFailsafe *AP::advancedfailsafe() { return nullptr; }

ArduSub/system.cpp

@@ -302,3 +302,9 @@ bool Sub::should_log(uint32_t mask)
     return false;
 #endif
 }
+
+#include <AP_AdvancedFailsafe/AP_AdvancedFailsafe.h>
+
+// dummy method to avoid linking AFS
+bool AP_AdvancedFailsafe::gcs_terminate(bool should_terminate, const char *reason) { return false; }
+AP_AdvancedFailsafe *AP::advancedfailsafe() { return nullptr; }