trivial: Remove the X- hack from parsing the category list
trivial: Remove the X- hack from parsing the category list

We already check the whitelist, so nothing changes really.

ximion/appstream-glib,hughsie/appstream-glib,ximion/appstream-glib,ximion/appstream-glib,hughsie/appstream-glib,hughsie/appstream-glib