chroot option + systemd do not coexist well

[zeha]

There are various issues when running pdns with chroot= set under systemd.

IIRC:

• notification to systemd fails because the systemd socket is unreachable
• pdns_control has (with some specific settings) trouble talking to the daemon

Personally, I'd think refusing to start under systemd with chroot set would be good.

[pieterlexis]

note:

Should be easy to detect, systemd creates the NOTIFY_SOCKET environment variable, we can refuse to start if it is present and chroot= is in the config