GetVersion and GetVersionEx were superseded by various version helper functions. The one you want is IsWindows10OrGreater. They can be found in VersionHelpers.h.
IsWindows10OrGreater is only available in the latest SDK/Visual Studio 2015. You can use IsWindowsVersionOrGreater in the general case however. For example on my 7 box I get TRUE for IsWindowsVersionOrGreater(6, 0, 0).
Remember that the parameters this function takes relate to Windows build number and NOT marketing name. So Windows 8 is build 6.2. Windows 7 is 6.0 etc.