[ft] Fix for CMakeLists.txt file?

[Paul Baker]

Hello,

Would it be possible to modify how the ftoption.h and ftconfig.h files are
created in the CMakeLists.txt file? These files are recreated every time
the cmake generation command is called even if the files already exist and
no changes are required. It would be much better to use the configure_file
command in cmake to only update the files if their contents have changed.

Thank you,

Paul Baker