Nobody should call anything "GNU/Linux". That name is just stupid.
Call it "Fedora" or "Ubuntu" or whatever else when you're talking about the distribution. And when you're talking about the standard system, it's just "Linux". The GNU tools are neither the majority nor the most important part, there's no point in pointing them out.
You wouldn't call Windows "GNU/Windows" just because you installed mingw on it, now would you?