/usr/lib/x86_64-linux-gnu/liboctave.so is in liboctave-dev 4.0.3-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/liboctave.so.3.0.2
/usr/lib/x86_64-linux-gnu/liboctave.so.3.0.2