MDEV-28892 remove #ifdef SPIDER_Item_args_arg_count_IS_PROTECTED

arg_count was protected since 2015 in commit
afa17734

storage/spider/spd_db_oracle.cc

@@ -3092,11 +3092,7 @@ int spider_db_oracle_util::open_item_func(
       {
         if (
           !strncasecmp("rand", func_name, func_name_length) &&
-#ifdef SPIDER_Item_args_arg_count_IS_PROTECTED
           !item_func->argument_count()
-#else
-          !item_func->arg_count
-#endif
         ) {
           if (str)
             str->length(str->length() - SPIDER_SQL_OPEN_PAREN_LEN);

storage/spider/spd_include.h

@@ -90,8 +90,6 @@
 #define SPIDER_ENGINE_CONDITION_PUSHDOWN_IS_ALWAYS_ON
 #define SPIDER_XID_USES_xid_cache_iterate
 
-#define SPIDER_Item_args_arg_count_IS_PROTECTED
-
 #define SPIDER_Item_func_conv_charset_conv_charset collation.collation
 
 #define SPIDER_WITHOUT_HA_STATISTIC_INCREMENT