/usr/alpha-linux-gnu/lib/libgnatprj.so is in libgnatprj5-dev-alpha-cross 5.5.0-12ubuntu1cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/alpha-linux-gnu/lib/libgnatprj.so.5
/usr/alpha-linux-gnu/lib/libgnatprj.so.5