the author of runkit seems dropped the dev for php7....
Modifying Constants, Functions, Classes, and Methods as well as Custom Superglobals works with all releases of PHP 5. No special requirements are necessary.
Sandboxing requires PHP 5.1.0 or later, or PHP 5.0.0 with a special TSRM patch applied. Regardless of which version of PHP is in use it must be compiled with the --enable-maintainer-zts option. See the README file in the runkit package for additional information.