add stock status to children products (#4100)

Co-authored-by: Sven Reichel <[email protected]>

app/code/core/Mage/ConfigurableSwatches/Helper/Mediafallback.php

@@ -425,6 +425,7 @@ public function attachChildrenProducts(array $products, $storeId)
         );
 
         $collection->setFlag('product_children', true)
+            ->setFlag('require_stock_items', true)
             ->addStoreFilter($storeId)
             ->addAttributeToSelect($this->_getChildrenProductsAttributes());
         $collection->addProductSetFilter($productIds);