patch 8.2.0523: loops are repeated

Problem:    Loops are repeated.
Solution:   Use FOR_ALL_ macros. (Yegappan Lakshmanan, closes #5882)
diff --git a/src/drawscreen.c b/src/drawscreen.c
index c60d75b..be4d6aa 100644
--- a/src/drawscreen.c
+++ b/src/drawscreen.c
@@ -963,7 +963,7 @@
     int		button_attr = syn_name2attr((char_u *)"ToolbarButton");
 
     vim_free(wp->w_winbar_items);
-    for (menu = wp->w_winbar->children; menu != NULL; menu = menu->next)
+    FOR_ALL_CHILD_MENUS(wp->w_winbar, menu)
 	++item_count;
     wp->w_winbar_items = ALLOC_CLEAR_MULT(winbar_item_T, item_count + 1);