Revert "opengl32: Return a NULL pointer for functions requiring unsupported or disabled extensions.".

[Alexandre Julliard]

Henri Verbeet <hverbeet at gmail.com> writes:

> Essentially, I think the number of affected users doesn't outweigh
> doing the correct thing in this case.

Correct me if I'm wrong, but isn't this simply a matter of returning
glCopyTexSubImage3D if glCopyTexSubImage3DEXT is missing?  That seems a
better solution than relying on quirks of the Nvidia driver.

Could someone please give this a try so that we can solve this
regression for 1.8?

-- 
Alexandre Julliard
julliard at winehq.org