Bug 27650: Fix variable passed to the template in opac-main

Bug 27650: Fix variable passed to the template in opac-main

$template->param(
+    koha_news           => @all_koha_news,

We must not pass an array, the number of elements of the hash passed to the template may be inconsistent.

It's working because of an error earlier in the script:
+    @all_koha_news   = &GetNewsToDisplay($news_lang,$homebranch);

GetNewsToDisplay returns an arrayref

Test plan:
Define at least 2 news to display on the OPAC main page
Hit opac-main.pl
=> All news are displayed
Click one
=> You see the single news you selected

Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>