/usr/lib/x86_64-linux-gnu/libgnatvsn.so is in libgnatvsn6-dev 6.4.0-17ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgnatvsn.so.6
/usr/lib/x86_64-linux-gnu/libgnatvsn.so.6