I just searched through the source code. And no version command, variable, or constant exists for (or that correlates to) a DarkGDK version. Although my search was only for anything containing "version" in it. It would have been nice if they'd thought about that earlier.
What you could do though is add it yourself as a #defined constant in one of the include files for all versions that you have. That way you could get your own code to work with all versions, if you wanted to... for example to see if a later version broke something that had worked earlier.
Judging what we see is the greatest blinder and self-limiter in the universe.
What we perceive is never reality. It is only a story we tell ourselves based on our current perspective, which has far more to do with our beliefs about ourselves than with anything else.