Bug 10663: restore ability of active hold requests to block renewal

Bug 10663: restore ability of active hold requests to block renewal

Sponsored-by: Universidad Nacional de Cordoba
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
This reverts changes made to CanBookBeRenewed by
patches from bug 9367.
GetReserveStatus is not suitable to recognize if an item
can fild a hold on return and CheckReserves is restored.

Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
This patch includes a squash of a follow-up authored by
Katrin Fischer <Katrin.Fischer.83@web.de>:

  CheckReserves returns '' when no reserve is found,
  so $resfound will always be defined and we need to
  check if it's true.

Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>