added split to depricated functions.

[aghontpi]

This function was actually DEPRECATED in PHP 5.3.0.

You can see the deprecated function list containing split in https://www.php.net/manual/en/migration53.deprecated.php under Migrating from PHP 5.2.x to PHP 5.3.x, but the function was "only" removed from php 7.0,

Migration guide of phpmanual(5.6.x to 7.0.x) does not include this for some reason.