patch 8.2.0389: delayed redraw when shifting text from Insert mode

Problem:    Delayed redraw when shifting text from Insert mode.
Solution:   Use msg_attr_keep() instead of msg(). (closes #5782)
diff --git a/src/ops.c b/src/ops.c
index d4b842c..08209c7 100644
--- a/src/ops.c
+++ b/src/ops.c
@@ -203,7 +203,7 @@
 	vim_snprintf((char *)IObuff, IOSIZE,
 		NGETTEXT(msg_line_single, msg_line_plural, oap->line_count),
 		oap->line_count, op, amount);
-	msg((char *)IObuff);
+	msg_attr_keep((char *)IObuff, 0, TRUE);
     }
 
     if (!cmdmod.lockmarks)