If you are using prebuild packages, PHP-extension's package naming has changed from php5-scache to php-scache to better fit for both PHP5 and PHP7.x -series. You probably need to uninstall the php5-scache before installing php-scache.
Previous archived versions
Prebuild packages are available on deb-based distributions below. Please note that you need both php5-scache and scached -packages.
For other unlisted debian-based systems you can rebuild packages yourself with "./debian/rules binary" from source tarball. For rpm-based distributions I have no idea how spec-files should be crafted so I make silent wish someone provides me a suitable one.