/usr/powerpc-linux-gnu/lib/libgnatprj.so is in libgnatprj6-dev-powerpc-cross 6.4.0-17ubuntu1cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/powerpc-linux-gnu/lib/libgnatprj.so.6
/usr/powerpc-linux-gnu/lib/libgnatprj.so.6