patch 8.1.0442: GUI: cursor not drawn after ":redraw | sleep"

Problem:    GUI: Cursor not drawn after ":redraw | sleep".
Solution:   Flush the output. (closes #3496)
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 82904ee..25d70c4 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -9272,7 +9272,7 @@
     long	wait_now;
 
     cursor_on();
-    out_flush();
+    out_flush_cursor(FALSE, FALSE);
     for (done = 0; !got_int && done < msec; done += wait_now)
     {
 	wait_now = msec - done > 1000L ? 1000L : msec - done;