Breaking: #87583 - Remove obsolete APC Cache Backend implementation

See forge#87583

Description

The Caching framework backend implementation \TYPO3\CMS\Core\Cache\Backend\ApcBackend has been removed. The APCu PHP extension has superseded in PHP 7.x.

Impact

The PHP APC extension works until PHP 5.x. APCu can be used as "drop-in" replacement since TYPO3 8 LTS which supports PHP 7.0+.

Affected Installations

Any installation which has been updated, and any legacy APC cache backend is configured (see LocalConfiguration.php).

Migration

Use APCu implementation, which is implemented via \TYPO3\CMS\Core\Cache\Backend\ApcuBackend instead of \TYPO3\CMS\Core\Cache\Backend\ApcBackend in your caching framework configuration.

Example before:

$GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations']['rootline']['backend'] = \TYPO3\CMS\Core\Cache\Backend\ApcBackend::class;

Example after:

$GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations']['rootline']['backend'] = \TYPO3\CMS\Core\Cache\Backend\ApcuBackend::class;