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