#130 [PHP]Return values are not good for cubrid_get_autocommit

[Jira Trac]

[cubrid_get_autocommit|http://www.php.net/manual/en/function.cubrid-get-autocommit.php] will return false when auto-commit is off and there is an error. It means we have to analysis the error message to ensure whether the auto-commit mode is off or there is an error.

Absolutely we don't want this confusing return value. So we modify it. When the auto-commit mode is off, we will return false, and when there is an error, we will return nothing.