/usr/lib/x86_64-linux-gnu/liballegro_main.so is in liballegro5-dev 2:5.0.10-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/liballegro_main.so.5.0
/usr/lib/x86_64-linux-gnu/liballegro_main.so.5.0