patch 9.0.0505: various problems with 'nosplitscroll'

Problem:    Various problems with 'nosplitscroll'.
Solution:   Fix 'nosplitscroll' problems. (Luuk van Baal, closes #11166)
diff --git a/src/globals.h b/src/globals.h
index 568d3b3..fee2951 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -1742,3 +1742,7 @@
 // Skip win_fix_cursor() call for 'nosplitscroll' when cmdwin is closed.
 EXTERN int skip_win_fix_cursor INIT(= FALSE);
 #endif
+// Skip win_fix_scroll() call for 'nosplitscroll' when closing tab page.
+EXTERN int skip_win_fix_scroll INIT(= FALSE);
+// Skip update_topline() call while executing win_fix_scroll().
+EXTERN int skip_update_topline INIT(= FALSE);