I also have issues installing the package that way, but not with python 3, with ImfTiledMisc.
CPPFLAGS="-L/home/lmnp/knut0297/software/modules/libffi/3.3/build/lib64 -I/home/lmnp/knut0297/software/modules/libffi/3.3/build/include" \ LDFLAGS="-L/home/lmnp ...