[BUGFIX] compatibility6: add class alias for backend_cacheActionsHook

This adds the class alias for backend_cacheActionsHook to
the ClassAliasMap.php of compitability6.

Change-Id: Ia42eb48d0be7886fd9c86ac7ce1bcf0b3b5840f8
Resolves: #66522
Releases: master
Reviewed-on: http://review.typo3.org/38851


Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>
Reviewed-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Tested-by: Mathias Schreiber <mathias.schreiber@wmdb.de>