/usr/lib/x86_64-linux-gnu/libgnatvsn.so is in libgnatvsn4.8-dev 4.8.2-8ubuntu3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgnatvsn.so.4.8
/usr/lib/x86_64-linux-gnu/libgnatvsn.so.4.8