This » PECL extension is not bundled with PHP.
Information for installing this PECL extension may be found in the manual chapter titled Installation of PECL extensions. Additional information such as new releases, downloads, source files, maintainer information, and a CHANGELOG, can be located here: » http://pecl.php.net/package/runkit.
The DLL for this PECL extension may be downloaded from either the » PHP Downloads page or from » http://pecl4win.php.net/