/usr/bin/powerpc-linux-gnu-gnatprep is in gnat-7-powerpc-linux-gnu 7.3.0-16ubuntu3cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/bin/powerpc-linux-gnu-gnatprep-7
/usr/bin/powerpc-linux-gnu-gnatprep-7