Bug 12871 - wthdrawn instead of withdrawn in ILSDI

Bug 10550 as renamed items.wthdrawn into items.withdrawn.
This change was missing in ILSDI/Services.pm

Test plan :
Test ILSDI webservice GetAvailability on a item with items.withdrawn > 0.

Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Fixes what seems to be the last occurence of wthdrawn.

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>

C4/ILSDI/Services.pm

@@ -772,7 +772,7 @@ sub _availability {
         return ( $biblionumber, 'not available', 'Checked out', $location );
     } elsif ( $item->{'itemlost'} ) {
         return ( $biblionumber, 'not available', 'Item lost', $location );
-    } elsif ( $item->{'wthdrawn'} ) {
+    } elsif ( $item->{'withdrawn'} ) {
         return ( $biblionumber, 'not available', 'Item withdrawn', $location );
     } elsif ( $item->{'damaged'} ) {
         return ( $biblionumber, 'not available', 'Item damaged', $location );