a syslog image will log everything it receives on stdout; so every
service that has a hard time logging can just send everything to it.
apache/ttrss configured to do it.
this is a big change: OpenRC introduced to tt-rss container.
However, this also means that environment variables set in
docker-compose.yml are not passed to apache.
also, state dirs are moved to /var/cache/ and /var/lock/, thus avoiding
their unneeded "copy" to host.
ICONS_DIR is still pointing to documentroot, so this is not yet
complete.
