/usr/mips64el-linux-gnuabi64/bin/ar is in binutils-mips64el-linux-gnuabi64 2.30-15ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/mips64el-linux-gnuabi64/bin/../../bin/mips64el-linux-gnuabi64-ar