kconfig: remove string expansion for mainmenu after yyparse()

Now that environments are expanded in the lexer, conf_parse() does
not need to expand them explicitly.

The hack introduced by commit 0724a7c3 ("kconfig: Don't leak
main menus during parsing") can go away.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Ulf Magnusson <ulfalizer@gmail.com>

scripts/kconfig/zconf.y

@@ -109,7 +109,7 @@ static struct menu *current_menu, *current_entry;
 %%
 input: nl start | start;
 
-start: mainmenu_stmt stmt_list | no_mainmenu_stmt stmt_list;
+start: mainmenu_stmt stmt_list | stmt_list;
 
 /* mainmenu entry */
 
@@ -118,19 +118,6 @@ mainmenu_stmt: T_MAINMENU prompt nl
 	menu_add_prompt(P_MENU, $2, NULL);
 };
 
-/* Default main menu, if there's no mainmenu entry */
-
-no_mainmenu_stmt: /* empty */
-{
-	/*
-	 * Hack: Keep the main menu title on the heap so we can safely free it
-	 * later regardless of whether it comes from the 'prompt' in
-	 * mainmenu_stmt or here
-	 */
-	menu_add_prompt(P_MENU, xstrdup("Linux Kernel Configuration"), NULL);
-};
-
-
 stmt_list:
 	  /* empty */
 	| stmt_list common_stmt
@@ -528,7 +515,6 @@ word_opt: /* empty */			{ $$ = NULL; }
 
 void conf_parse(const char *name)
 {
-	const char *tmp;
 	struct symbol *sym;
 	int i;
 
@@ -544,10 +530,10 @@ void conf_parse(const char *name)
 	if (!modules_sym)
 		modules_sym = sym_find( "n" );
 
-	tmp = rootmenu.prompt->text;
-	rootmenu.prompt->text = rootmenu.prompt->text;
-	rootmenu.prompt->text = sym_expand_string_value(rootmenu.prompt->text);
-	free((char*)tmp);
+	if (!menu_has_prompt(&rootmenu)) {
+		current_entry = &rootmenu;
+		menu_add_prompt(P_MENU, "Linux Kernel Configuration", NULL);
+	}
 
 	menu_finalize(&rootmenu);
 	for_all_symbols(i, sym) {