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

[Henri Verbeet]

On 27 November 2015 at 06:21, Alexandre Julliard <julliard at winehq.org> wrote:
>> 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.
>
I think so, yeah.