Bug 17157: Fix middle click on "Search" drowndown menu

Bug 17157: Fix middle click on "Search" drowndown menu

If you save an item and right click on "Search" or "More" you will get
a software error:
Can't call method "fields" on an undefined value at
/usr/share/koha/intranet/cgi-bin/cataloguing/additem.pl line 742

You will now be redirected to the adv search form.

Wors as described.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Katrin Fischer  <katrin.fischer@bsz-bw.de>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit 1fe9c40da4e71bde460133ee6248503ce1025999)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>