patch 9.0.1568: with 'smoothscroll' cursor may move below botline

Problem:    With 'smoothscroll' cursor may move below botline.
Solution:   Call redraw_later() if needed,  Compute cursor row with adjusted
            condition. (Luuk van Baal, closes #12415)
diff --git a/src/version.c b/src/version.c
index 42c2c0f..54d927e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1568,
+/**/
     1567,
 /**/
     1566,