filechooser: Translate type column

When the code for this was copied from nautilus,
we forgot to adapt it for running in a library
instead of an application - gettext() doesn't work
in a library.

Fixes: #2690

gtk/gtkfilechooserwidget.c

@@ -5028,7 +5028,7 @@ get_category_from_content_type (const char *content_type)
         {
           if (strcmp (mime_type_map[i].icon_name, icon_name) == 0)
             {
-              basic_type = g_strdup (gettext (mime_type_map[i].display_name));
+              basic_type = g_strdup (_(mime_type_map[i].display_name));
               break;
             }
         }