Bug 22101: Ill Requests missing in menu on advanced search page

Bug 22101: Ill Requests missing in menu on advanced search page

This patch adds [% USE Koha %] to header.inc so that Koha.Preference
calls will work correctly.

To test, apply the patch and log in to the staff client as a user who
has permission to access the ILL module.

- Go to the catalog's advanced search page
- Cnfirm there is a header menu item under "More" for
  "ILL requests."

Signed-off-by: Maryse Simard <maryse.simard@inlibro.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>