/usr/s390x-linux-gnu/lib/libgnarl.so is in gnat-5-s390x-linux-gnu 5.5.0-12ubuntu1cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/s390x-linux-gnu/lib/libgnarl-5.so.1
/usr/s390x-linux-gnu/lib/libgnarl-5.so.1