/usr/mips64el-linux-gnuabi64/lib/libgnat.so is in gnat-8-mips64el-linux-gnuabi64 8-20180414-1ubuntu2cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/mips64el-linux-gnuabi64/lib/libgnat-8.so.1