Fixed compilation error if HAVE_CRYPT is not defined

sql/item_strfunc.cc

@@ -2203,9 +2203,10 @@ char *Item_func_password::alloc(THD *thd, const char *password,
 String *Item_func_encrypt::val_str(String *str)
 {
   DBUG_ASSERT(fixed == 1);
-  String *res  =args[0]->val_str(str);
 
 #ifdef HAVE_CRYPT
+  String *res  =args[0]->val_str(str);
+
   char salt[3],*salt_ptr;
   if ((null_value=args[0]->null_value))
     return 0;