patch 8.1.2313: debugging where a delay comes from is not easy

Problem:    Debugging where a delay comes from is not easy.
Solution:   Use different values when calling ui_delay().
diff --git a/src/buffer.c b/src/buffer.c
index f7ff01f..cba84c6 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -2103,7 +2103,7 @@
 	    if (emsg_silent == 0)
 	    {
 		out_flush();
-		ui_delay(3000L, TRUE);	/* make sure it is noticed */
+		ui_delay(3001L, TRUE);	// make sure it is noticed
 	    }
 	    top_file_num = 1;
 	}