gerrit: make Apache config compatible with 2.4
Making the Gerrit Apache config compatible with 2.2 and 2.4
It may also work without this but only if/because mod_access_compat is
This module is loaded now by default but will be removed in the next
distro version. So this change makes it future-proof and it does not
rely on the special module and it will be untouched on the old server.