/usr/include/erl_nif.h is in erlang-dev 1:18.3-dfsg-1ubuntu3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/include/../lib/erlang/usr/include/erl_nif.h
/usr/include/../lib/erlang/usr/include/erl_nif.h