FIX #2957 : missing $langs object for trigger

htdocs/fourn/class/fournisseur.product.class.php

@@ -156,7 +156,7 @@ class ProductFournisseur extends Product
      */
     function update_buyprice($qty, $buyprice, $user, $price_base_type, $fourn, $availability, $ref_fourn, $tva_tx, $charges=0, $remise_percent=0, $remise=0, $newnpr=0)
     {
-        global $conf,$mysoc;
+        global $conf,$mysoc, $langs;
 
         // Clean parameter
         if (empty($qty)) $qty=0;