Fix for Bug 6600, Library name linking wrong if current location is different

Fix for Bug 6600, Library name linking wrong if current location is different

GetItemsInfo in Items.pm includes this join:

LEFT JOIN branches ON items.homebranch = branches.branchcode

This means that the branch URL (from the branches table) comes out
as the URL for items.homebranch, thus the URL in the holdings
output is the item's home branch even though the display might
be showing a different current location.

This patch changes the join to use items.holdingbranch. The join
was originally added to fix Bug 3702, and based on the description
of that feature I'm assuming this change is not harmful to other
usages. However, it does make the assumption that the item's
current (holding) branch is the branch we want to see information
about.

Signed-off-by: Nicole Engard <nengard@gmail.com>
Signed-off-by: Ian Walls <ian.walls@bywatersolutions.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>