This one is available since APCu 4.0, since we require APCu 4.0.6 this works fine. Also it brings us PHP 7 compatibility and thus fixes https://github.com/owncloud/core/issues/21095
APCu before 4.0.6 is unbelievable buggy and tend to segfault the PHP process (i.e. the whole webserver)
This potentially fixes https://github.com/owncloud/core/issues/14175
Requires a backport to stable8