patch 9.0.1543: display errors when making topline shorter

Problem:    Display errors when making topline shorter and 'smoothscroll' is
            set.
Solution:   Reset w_skipcol when the topline becomes shorter than its current
            value. (Luuk van Baal, closes #12367)
diff --git a/src/version.c b/src/version.c
index 4c70def..dd6baa9 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1543,
+/**/
     1542,
 /**/
     1541,