patch 9.0.0469: cursor moves if cmdwin is closed when 'splitscroll' is off

Problem:    Cursor moves if cmdwin is closed when 'splitscroll' is off.
Solution:   Skip win_fix_cursor if called when cmdwin is open or closing.
            (Luuk van Baal, closes #11134)

src/window.c

@@ -6410,6 +6410,10 @@ win_fix_cursor(int normal)
 
     if (wp->w_buffer->b_ml.ml_line_count < wp->w_height)
 	return;
+#ifdef FEAT_CMDWIN
+    if (skip_win_fix_cursor)
+	return;
+#endif
 
     so = MIN(wp->w_height / 2, so);
     // Check if cursor position is above topline or below botline.