Bug 9224: Make acqui/finishreceive.pl Plack-compatible

Bug 9224: Make acqui/finishreceive.pl Plack-compatible

Under Plack/mod_perl wrapping, sub update_item() will become a closure,
so after the 1st run it will retain its own private instances of the
following variables: $booksellerid, $datereceived, $unitprice, $rrp,
$biblionumber.

I.e., in case update_item() gets invoked 2nd+ time (inside
the same process, but for different-subsequent receives) it may
incorrectly flag the (old, wrong) biblionumber for Zebra reindexing,
and erronously modify the current item[s] with the previously
used (wrong) values.

This simple patch should make acqui/finishreceive.pl Plack-compatible.

Test plan:
Test patched acqui/finishreceive.pl script (create and receive some
orders w/ items, etc.). Ensure items are gettting added and/or modified
correctly during receiving process.

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Passes koha-qa.pl, works as advertised, no regressions found.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>