Bug 29791: KohaOpacLanguage cookie should set the secure flag if using https

To test, the headers should have value set-cookie: secure;
for the language cookie, when the site is using https.

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>

C4/Templates.pm

@@ -349,6 +349,7 @@ sub getlanguagecookie {
         -value   => $language,
         -HttpOnly => 1,
         -expires => '+3y'
+        -secure => ( C4::Context->https_enabled() ? 1 : 0 ),
     );
 
     return $cookie;