[CMake] cmake -E create_symlink for Windows

[Marcel Loose]

Hi all,

I was browsing the CMake sources for a problem I was facing with the
creation of symlinks (on Unix that is) and I noticed that the
SystemTools::CreateSymlink function simply returns false when building
on a Windows platform. 

Does that mean that I cannot use 'cmake -E create_symlink' on Windows.
If that's the case I consider it a bug, because the documentation
suggests that 'cmake -E create_symlink' provides a platform independent
way of creating symbolic links. So, if the OS and/or filesystem does not
support symbolic links, IMHO, it should just copy the file.

Best regards,
Marcel Loose.