There is no swap on any of our machines. Additionally, mem+swap
accounting is disabled in the default Debian kernel. We have no reason
to enable it. (It can just consume more memory.)

Daemonization is handled by systemd.

It makes a mess when somebody else is already managing the cgroups.

Compctl client now works as simple server-less agent if
/etc/compctl-unlimited exists; so-called 'kamenolom mode'.

Currently, the init script would kill itself

TODO: Partially autogenerate from README.client too.

Can be disabled in common.h in case your kernel does not support it.

Pointed out by Stick.

sendmsg() with only ancilliary message does not work, apparently.
Therefore, to make things cleaner, pass command/reply directly using
sendmsg() instead of newline-terminated strings.