Add new GLOBAL STATUS for MariaDB 10.4

The goal is to increase efficiently of tool's monitoring and get

SHOW /*!40003 GLOBAL*/ VARIABLES;

only when we need it.

The goal is to add a new GLOBAL STATUS with name : Com_set_global_variables (who only affected when we update this, for all server like with SET GLOBAL XXXXX=YY;

I know there is Com_set_option, but when we do

SET NAMES utf8;

it's update to +1 to Com_set_option and I don't want this because most of ORM and Apps made this. (like AUTOCOMMIT)