close FD after busshutdown

(cherry picked from commit e136fb89)

source/RobotAPI/libraries/ArmarXEtherCAT/EtherCATRTUnit.cpp

@@ -279,6 +279,15 @@ void EtherCATRTUnit::rtRun()
         //switching off the bus and be sure that the bus will receive
         bus.switchBusOFF();
         bus.updateBus();
+        if (getProperty<int>("SocketFileDescriptor").isSet() && getProperty<int>("SocketFileDescriptor").getValue() > 0)
+        {
+            ARMARX_INFO << "Closing raw socket with FD " << getProperty<int>("SocketFileDescriptor").getValue();
+            int ret = close(getProperty<int>("SocketFileDescriptor").getValue());
+            if (ret)
+            {
+                ARMARX_INFO << "Failed to close raw socket file handle: " << ret << " errno: " << strerror(errno);
+            }
+        }
     };