HAL_PX4: implement set_system_clock()

libraries/AP_HAL_PX4/Util.cpp

@@ -89,4 +89,12 @@ enum PX4Util::safety_state PX4Util::safety_switch_state(void)
     return AP_HAL::Util::SAFETY_DISARMED;
 }
 
+void PX4Util::set_system_clock(uint64_t time_utc_usec)
+{
+    timespec ts;
+    ts.tv_sec = time_utc_usec/1.0e6;
+    ts.tv_nsec = (time_utc_usec % 1000000) * 1000;
+    clock_settime(CLOCK_REALTIME, &ts);    
+}
+
 #endif // CONFIG_HAL_BOARD == HAL_BOARD_PX4

libraries/AP_HAL_PX4/Util.h

@@ -12,6 +12,11 @@ public:
 
     enum safety_state safety_switch_state(void);
 
+    /*
+      set system clock in UTC microseconds
+     */
+    void set_system_clock(uint64_t time_utc_usec);
+
 private:
     int _safety_handle;
 };