Its from a setup script.
wget http://malus.exotica.org.uk/~buzz/pi/sdl/sdl1/deb/rpi2/libsdl1.2debian_1.2.15-8rpi_armhf.deb
wget http://malus.exotica.org.uk/~buzz/pi/sdl/sdl2/libsdl2_2.0.3_armhf.deb
sudo dpkg -i libsdl*
sudo apt-mark hold libsdl1.2debian
sudo apt-mark hold libsdl2
Looking up libsdl it seems its a low level hook. And it looks like they are downloading a custom version from some shady website and telling it not to overwrite on an automatic update. I cant get into the files and see exactly what it does, it seems to be compiled. I dont see the reason for installing this either.