patch 9.0.0892: may redraw when not needed

Problem:    May redraw when not needed, causing slow scrolling.
Solution:   Do not redraw when w_skipcol doesn't change.  When w_skipcol
            changes only redraw from the top. (issue #11559)
diff --git a/src/testdir/Make_all.mak b/src/testdir/Make_all.mak
index 04ccb48..1ac29b1 100644
--- a/src/testdir/Make_all.mak
+++ b/src/testdir/Make_all.mak
@@ -484,6 +484,7 @@
 	test_retab.res \
 	test_ruby.res \
 	test_scriptnames.res \
+	test_scroll_opt.res \
 	test_scrollbind.res \
 	test_search.res \
 	test_search_stat.res \