[vtkusers] find VTK library dependencies automatically

[John Drescher]

> Thanks, John.
> Does that mean I need to manually append all the dependent libraries into
> CMakeLists.txt?
>

I am sorry. I do not know that answer (if that is absolutely required)
because I have not looked at it that closely. For my vtk projects I
just append the 2 or 3 vtk libs to my TARGET_LINK_LIBRARIES and do not
think much about it since it always works..

John