client: make ETA interval poll period configurage in fio_client_ops

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/client.h b/client.h
index caeb432..9668afa 100644
--- a/client.h
+++ b/client.h
@@ -83,6 +83,7 @@
 	client_add_job_op add_job;
 	client_timed_out timed_out;
 	client_stop_op stop;
+	unsigned int eta_msec;
 	int stay_connected;
 };
 
@@ -118,5 +119,7 @@
 extern struct fio_client *fio_get_client(struct fio_client *);
 extern void fio_put_client(struct fio_client *);
 
+#define FIO_CLIENT_DEF_ETA_MSEC		900
+
 #endif