BARO_generic: add Dummy GCS to meet the requirement of AP_Baro::calibrate().

libraries/AP_Baro/examples/BARO_generic/BARO_generic.cpp

@@ -5,6 +5,8 @@
 #include <AP_Baro/AP_Baro.h>
 #include <AP_BoardConfig/AP_BoardConfig.h>
 #include <AP_HAL/AP_HAL.h>
+#include <GCS_MAVLink/GCS_Dummy.h>
+
 
 const AP_HAL::HAL &hal = AP_HAL::get_HAL();
 
@@ -67,4 +69,10 @@ void loop()
     }
 }
 
+const struct AP_Param::GroupInfo        GCS_MAVLINK::var_info[] = {
+    AP_GROUPEND
+};
+GCS_Dummy _gcs;
+
+
 AP_HAL_MAIN();