I have serious doubts that this would be sufficient. The DirectFB library will probably dl() other libraries, here those residing in /usr/lib/directfb-1.2-0/. So those would be needed, too. Maybe there are some resource bits in /usr/share, too.
Also, I would suggest to be very careful when it comes to add things to the root file system. Later Updates tend to make assumptions about available storage and may fail badly when things really go wrong.
To make things worse, DirectFB might itself pull in other dependencies (font handling comes to my mind) and chances are that at some point there will be binary incompatibilities.