Resolve "named support of a systemd unit with 'notify-reload' service type is incomplete"
When using sd_notify(3) to send a message to the service manager about named being reloaded, systemd also requires the MONOTONIC_USEC field to be set to the current monotonic time in microseconds, otherwise the 'systemctl reload' command fails.
Add the MONOTONIC_USEC field to the message.
See 'man 5 systemd.service' for more information.
Closes #4377 (closed)