Note by reviewer (Jehan): merging this port as it was in GIMP 2.10
anyway, but is this even still needed code? This plug-in is not even
available on stable release, it looks like for-development only
benchmark, and I'm not sure if it's relevant anymore, especially in our
GEGL-fueled new world.
Please anyone who knows a bit more on the history of this plug-in and
the evolution of our gimp_drawable_foreground_extract() algorithm, feel
free to weigh in and tell us what this was for exactly and if it's still
relevant.
