BUG/MINOR: queue: properly report redistributed connections

In commit 5cd4bbd7a ("BUG/MAJOR: threads/queue: Fix thread-safety issues
on the queues management") the counter of transferred connections was
accidently lost, so that when a server goes down with connections in its
queue, it will always be reported that 0 connection were transferred.

This should be backported as far as 1.8 since the patch above was
backported there.

src/queue.c

@@ -416,6 +416,7 @@ int pendconn_redistribute(struct server *s)
 		p->strm_flags &= ~(SF_DIRECT | SF_ASSIGNED | SF_ADDR_SET);
 
 		task_wakeup(p->strm->task, TASK_WOKEN_RES);
+		xferred++;
 	}
 	return xferred;
 }