Rover: add and use AP_RPM_ENABLED

... and backend-specific equivalents

Rover/Parameters.cpp

@@ -357,9 +357,11 @@ const AP_Param::Info Rover::var_info[] = {
     GOBJECTN(ahrs.EKF3, NavEKF3, "EK3_", NavEKF3),
 #endif
 
+#if AP_RPM_ENABLED
     // @Group: RPM
     // @Path: ../libraries/AP_RPM/AP_RPM.cpp
     GOBJECT(rpm_sensor, "RPM", AP_RPM),
+#endif
 
     // @Group: MIS_
     // @Path: ../libraries/AP_Mission/AP_Mission.cpp

Rover/Rover.cpp

@@ -98,7 +98,9 @@ const AP_Scheduler::Task Rover::scheduler_tasks[] = {
     SCHED_TASK(update_precland,      400,     50,  70),
 #endif
 #endif
+#if AP_RPM_ENABLED
     SCHED_TASK_CLASS(AP_RPM,              &rover.rpm_sensor,       update,         10,  100,  72),
+#endif
 #if HAL_MOUNT_ENABLED
     SCHED_TASK_CLASS(AP_Mount,            &rover.camera_mount,     update,         50,  200,  75),
 #endif

Rover/Rover.h

@@ -129,8 +129,10 @@ private:
     AP_Int8 *modes;
     const uint8_t num_modes = 6;
 
+#if AP_RPM_ENABLED
     // AP_RPM Module
     AP_RPM rpm_sensor;
+#endif
 
     // Arming/Disarming management class
     AP_Arming_Rover arming;

Rover/system.cpp

@@ -35,8 +35,10 @@ void Rover::init_ardupilot()
 
     battery.init();
 
+#if AP_RPM_ENABLED
     // Initialise RPM sensor
     rpm_sensor.init();
+#endif
 
     rssi.init();