[CMake] FLTKConfig.cmake on Microsoft Windows

[Julia Jacobson]

> I think, the problem with FindFLTK is, that it has never been tested on
> Windows. If you take a look at FindFLTK you will detect the following
> lines:
>    # if FLTK was not built using CMake
>      # Find fluid executable.
>      FIND_PROGRAM(FLTK_FLUID_EXECUTABLE fluid ${FLTK_INCLUDE_DIR}/fluid)
>
>      # Use location of fluid to help find everything else.
>
> So on Windows everything is based on finding "fluid". If this fails then
> the whole detection-mechanism of finding the other components collapse.
>
>> Would it help to add the FLTK directory to the Windows PATH variable?
> In this case not. FindFLTK does not use it.

Well, but another solution that works for me is to rename the fluid 
application from fluidd.exe to fluid.exe and add the directory where it 
can be found to the PATH variable of the local Windows user.
Like this, CMake now finds the correct path of the FLTK installation.
Whether this solution is better than adding absolute PATHs to the 
CMakeLists.txt file depends on one's point of view.
The solution is at least worth while considering.

Thanks again for all your help and sorry for the noise,
Julia