Bug 27082: uncertainprice.pl does not handle pagination

Bug 27082: uncertainprice.pl does not handle pagination

To reproduce:
1- create a basket
2- add more of 20 orders with uncertain price
3- click on uncertain price button
4- on page 1 of list, uncheck uncertain box of an order
5- click on save button
6- orders who were on page 2 are not display anymore in page uncertainprice.pl
7- return to basket view acqui/basket.pl
8- orders who were on page 2 have "rvcd" label and quantity is null

The data in page 2 and beyond is not transmitted, but the code doesn't
handle that.  This patch makes sure that all that (empty) data is not (wrongly) processed.

Sponsored by: CCSR

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 5bc36cd672ad7d4abf839bed2d48da43f09415e9)

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>