[qtbase] add support to mariadb variant for QtSql

### Is your feature request related to a problem? Please describe. The QMYSQL module from the QtSql support Mysql and MariaDB as back-end. https://doc.qt.io/qt-6/sql-driver.html#qmysql-for-mysql-or-mariadb-5-6-and-higher For a licensing purpose, it will be a plus to support MariaDB in the list of SQL back-end variant of the QtBase package. A simple patch to enable this feature on the QtBase JSON configuration file is given below: "sql-mariadb": { "description": "Enable SQL Driver MariaDB", "dependencies": [ "libmariadb", { "name": "qtbase", "default-features": false, "features": [ "sql" ] } ] }, Note: The Macports project support both back-ends using a variant switch and it work well. ### Proposed solution Add the relevant lines given in the description in the QtBase JSON file to enable MariaDB support. ### Describe alternatives you've considered _No response_ ### Additional context _No response_