/usr/mipsel-linux-gnu/lib/libnss_nis.so is in libc6-dev-mipsel-cross 2.27-3ubuntu1cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/mipsel-linux-gnu/lib/libnss_nis.so.2
/usr/mipsel-linux-gnu/lib/libnss_nis.so.2