/usr/bin/powerpc64-linux-gnu-gnatprep is in gnat-6-powerpc64-linux-gnu 6.4.0-17ubuntu1cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/bin/powerpc64-linux-gnu-gnatprep-6
/usr/bin/powerpc64-linux-gnu-gnatprep-6