[php-src] Issue #10893: PHP 8.1 fatals when attempting to unserialize empty mysqli_result from PHP 8.0

Issue: https://github.com/php/php-src/issues/10893 Author: brandonpayton ### Description Given a mysqli connection $mysqli_connection, an empty mysqli_result instance can be created like new mysqli_result( $mysqli_connection ). Such an empty instance is serialized differently between PHP 8.0 and PHP 8.1, and PHP 8.1 fatals when attempting to deserialize the PHP 8.0 representation. In PHP 8.0, serialize( new mysqli_result( $mysqli_connection ) ) yields the string: O:13:"mysqli_result":5:{s:13:"current_field";N;s:11:"field_count";N;s:7:"lengths";N;s:8:"num_rows";N;s:4:"type";N;} The following code in PHP 8.1: ```php <?php var_dump( unserialize( 'O:13:"mysqli_result":5:{s:13:"current_field";N;s:11:"field_count";N;s:7:"lengths";N;s:8:"num_rows";N;s:4:"type";N;}' ) ); ``` Resulted in this output (tested via WP-CLI's wp shell command): ``` Fatal error: Uncaught TypeError: Cannot assign null to property mysqli_result::$current_field of type int in phar:///usr/local/bin/wp-cli/vendor/wp-cli/shell-command/src/WP_CLI/Shell/REPL.php(46) : eval()'d code:1 ``` But I expected output like this instead: ``` object(mysqli_result)#8072 (0) { } ``` PHP 8.0 produces output like that above, but PHP 8.1 fatals. This means that PHP 8.1 can fatal when attempting to unserialize data serialized by PHP 8.0. ### PHP Version PHP 8.1.17 ### Operating System _No response_