/usr/mips64el-linux-gnuabi64/lib/libnsl.so is in libc6-dev-mips64el-cross 2.23-0ubuntu3cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/mips64el-linux-gnuabi64/lib/libnsl.so.1
/usr/mips64el-linux-gnuabi64/lib/libnsl.so.1