pr-poll-loop: Do not add FD when events is empty

Signed-off-by: Jan Friesse <jfriesse@redhat.com>

qdevices/pr-poll-loop.c

@@ -279,6 +279,13 @@ int prepare_poll_array(struct pr_poll_loop *poll_loop)
 			return (-2);
 		}
 
+		if (events == 0) {
+			/*
+			 * Empty events -> do not add entry
+			 */
+			res = -1;
+		}
+
 		switch (res) {
 		case 0:
 			/*