glstate: Fix default arrayStride computation.
glstate: Fix default arrayStride computation.

I don't know of any particular case where this causes problems reading
uniforms, but this does cause problems reading vertex attributes in a
follow up commit.

schulmar/apitrace,apitrace/apitrace,apitrace/apitrace,trtt/apitrace,schulmar/apitrace,apitrace/apitrace,schulmar/apitrace,trtt/apitrace,schulmar/apitrace,trtt/apitrace,apitrace/apitrace,schulmar/apitrace,trtt/apitrace,trtt/apitrace