schedule() other processes while waiting in ec_master_sync_io().

TODO

@@ -8,7 +8,6 @@ $Id$
 
 * Release 1.2:
   - Find bug causing slow unloading after topology change.
-  - Use schedule() in ec_master_sync_io().
   - Introduce topology_change_pending.
   - Update feature lists.
 

master/master.c

@@ -1458,6 +1458,7 @@ void ec_master_sync_io(ec_master_t *master /**< EtherCAT master */)
     ecrt_master_send(master);
 
     while (1) { // active waiting
+        schedule(); // schedule other processes while waiting.
         ecrt_master_receive(master); // receive and dequeue datagrams
 
         // count number of datagrams still waiting for response