egl: QueryContext on a configless context returns zero

egl: QueryContext on a configless context returns zero

MESA_configless_context does not specify the interaction with
QueryContext at all, and the code to generate an error in this case
predates the Mesa extension. Since EGL_NO_CONFIG_{KHR,MESA} are
numerically identical there's no way to distinguish which one the
application asked for, so use the KHR behaviour.

Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Adam Jackson <ajax@redhat.com>