fix multi statement

[alpes214]

Description:
Fixes the issue #2631

Testing:
Tested with scripts related #2298 and #2631

single('SELECT @@report_host');
multi('SELECT 1; SELECT 2;');

$ php -f test_2631.php
Run using query: SELECT @@report_host
=> No errors

-----
Run using multi_query: SELECT 1; SELECT 2;
=> No errors
1
2
-----