patch 8.2.0979: a couple of screendump tests fail

Problem:    A couple of screendump tests fail.
Solution:   Do not redraw when clearing t_8u.
diff --git a/src/version.c b/src/version.c
index 2c2c573..3ac374f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    979,
+/**/
     978,
 /**/
     977,