/usr/lib/x86_64-linux-gnu/libslang.so is in libslang2-dev 2.3.1-5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /lib/x86_64-linux-gnu/libslang.so.2
/lib/x86_64-linux-gnu/libslang.so.2