kconfig: delay symbol direct dependency initialization

This fixes the use-after-free and associated crash in kconfig introduced
in commit 246cf9c26bf11f2bffbecea6e5bd222eee7b1df8.

Signed-off-by: Arnaud Lacombe <[e-mail]>
Acked-by: Catalin Marinas <[e-mail]>
Signed-off-by: Michal Marek <[e-mail]>

scripts/kconfig/expr.h

···
 	struct symbol *sym;
 	struct property *prompt;
 	struct expr *dep;
-	struct expr *dir_dep;
 	unsigned int flags;
 	char *help;
 	struct file *file;

scripts/kconfig/menu.c

···
 void menu_add_dep(struct expr *dep)
 {
 	current_entry->dep = expr_alloc_and(current_entry->dep, menu_check_dep(dep));
-	current_entry->dir_dep = current_entry->dep;
 }
 
 void menu_set_type(int type)
···
 		for (menu = parent->list; menu; menu = menu->next)
 			menu_finalize(menu);
 	} else if (sym) {
-		/* ignore inherited dependencies for dir_dep */
-		sym->dir_dep.expr = expr_transform(expr_copy(parent->dir_dep));
-		sym->dir_dep.expr = expr_eliminate_dups(sym->dir_dep.expr);
-
 		basedep = parent->prompt ? parent->prompt->visible.expr : NULL;
 		basedep = expr_trans_compare(basedep, E_UNEQUAL, &symbol_no);
 		basedep = expr_eliminate_dups(expr_transform(basedep));
···
 			parent->next = last_menu->next;
 			last_menu->next = NULL;
 		}
+
+		sym->dir_dep.expr = parent->dep;
 	}
 	for (menu = parent->list; menu; menu = menu->next) {
 		if (sym && sym_is_choice(sym) &&