/usr/s390x-linux-gnu/lib/libgnatprj.so is in libgnatprj5-dev-s390x-cross 5.3.1-14ubuntu2cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/s390x-linux-gnu/lib/libgnatprj.so.5
/usr/s390x-linux-gnu/lib/libgnatprj.so.5