/usr/bin/mips64-linux-gnuabi64-gnatprep is in gnat-8-mips64-linux-gnuabi64 8-20180414-1ubuntu2cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/bin/mips64-linux-gnuabi64-gnatprep-8
/usr/bin/mips64-linux-gnuabi64-gnatprep-8