Bug#818001: More bashisms

[Jakob Haufe]

retitle 818001 needrestart: bashisms in /etc/needrestart/notify.d/* prevent 
proper check
kthxbye

The same applies to 

* /etc/needrestart/notify.d/200-write
* /etc/needrestart/notify.d/400-notify-send

Cheers,
sur5r