Bug 14387: Merge reference selection has no effect when merging authorities.

Bug 14387: Merge reference selection has no effect when merging authorities.

This patch swaps the authority records according to the refenrece record selection.

To TEST:
Merge two authority records, select the second as merge reference.
The reference authority is always the first.

Apply the patch.
Repeat previous steps, the authority is now merged using the selected reference record.

	modified:   authorities/merge.pl

Signed-off-by: Nick Clemens <nick@quecheelibrary.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>