/usr/lib/x86_64-linux-gnu/libgnatprj.so is in libgnatprj4.9-dev 4.9.3-3ubuntu5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgnatprj.so.4.9
/usr/lib/x86_64-linux-gnu/libgnatprj.so.4.9