Bug 26817: Change checkouts table footer colspan based on ExportCircHistory

Bug 26817: Change checkouts table footer colspan based on ExportCircHistory

This patch makes a minor change to the include file which generates the
checkouts table footer. It now includes some logic checking for the
ExportCircHistory system preference, adjusting the colspan accordingly.

To test, apply the patch and enable the ExportCircHistory system
preference.

- Check out to a patron who has checkouts. In the table of checkouts
  there should be an "Export" column. The footer at the bottom of the
  table should span the width of the table.
- Disable the ExportCircHistory preference.
- View the checkout page again and confirm that table footer still looks
  correct.

Signed-off-by: Séverine QUEUNE <severine.queune@bulac.fr>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>