AP_HAL_Empty: added register_io_process()

libraries/AP_HAL_Empty/Scheduler.cpp

@@ -32,6 +32,9 @@ void EmptyScheduler::register_delay_callback(AP_HAL::Proc k,
 void EmptyScheduler::register_timer_process(AP_HAL::TimedProc k)
 {}
 
+void EmptyScheduler::register_io_process(AP_HAL::TimedProc k)
+{}
+
 void EmptyScheduler::register_timer_failsafe(AP_HAL::TimedProc,
             uint32_t period_us)
 {}

libraries/AP_HAL_Empty/Scheduler.h

@@ -16,6 +16,7 @@ public:
                 uint16_t min_time_ms);
 
     void     register_timer_process(AP_HAL::TimedProc);
+    void     register_io_process(AP_HAL::TimedProc);
     void     suspend_timer_procs();
     void     resume_timer_procs();