Accept no attributes in GetPlatformDisplayEXT. It is quite valid for the app to pass in NULL for the attribs list. In this case we currently crash. We could trigger this error using dEQP. Change-Id: I64aba1077f9095bd099c6b60f789ec076cb3d385 Reviewed-on: https://chromium-review.googlesource.com/238081 Tested-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>