patch 9.0.0316: screen flickers when 'cmdheight' is zero

Problem:    Screen flickers when 'cmdheight' is zero.
Solution:   Redraw over existing text instead of clearing.
diff --git a/src/version.c b/src/version.c
index 82b43be..4dbe100 100644
--- a/src/version.c
+++ b/src/version.c
@@ -708,6 +708,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    316,
+/**/
     315,
 /**/
     314,