[Minor] Fix return values

contrib/libev/ev_iouring.c

 iouring_sqe_get (EV_P)
 {
   unsigned tail;
-  
+
   for (;;)
     {
       tail = EV_SQ_VAR (tail);
   EV_SQ_ARRAY [idx] = idx;
   ECB_MEMORY_FENCE_RELEASE;
   ++EV_SQ_VAR (tail);
-  /*ECB_MEMORY_FENCE_RELEASE; /* for the time being we assume this is not needed */
+  // ECB_MEMORY_FENCE_RELEASE; /* for the time being we assume this is not needed */
   ++iouring_to_submit;
+  return sqe;
 }
 
 /*****************************************************************************/
       ev_ref (EV_A);
       ev_io_stop (EV_A_ &iouring_tfd_w);
     }
+
+  return 0;
 }
 
 ecb_cold
 iouring_handle_cq (EV_P)
 {
   unsigned head, tail, mask;
-  
+
   head = EV_CQ_VAR (head);
   ECB_MEMORY_FENCE_ACQUIRE;
   tail = EV_CQ_VAR (tail);