Bug 20799: (follow-up) Add ILLModule system preference check and fix display for...

Bug 20799: (follow-up) Add ILLModule system preference check and fix display for no requests

When there were no requests the label would still display, using .count fixes this.
Also adds a check on the ILLModule system preference to prevent the information from
showing when the ILL module is deactivated.

Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>