/usr/mipsisa64r6-linux-gnuabi64/lib/libnsl.so is in libc6-dev-mips64r6-cross 2.27-3ubuntu1cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/mipsisa64r6-linux-gnuabi64/lib/libnsl.so.1
/usr/mipsisa64r6-linux-gnuabi64/lib/libnsl.so.1