/usr/include/erl_interface.h is in erlang-dev 1:15.b.1-dfsg-4+deb7u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/include/../lib/erlang/lib/erl_interface-3.7.7/include/erl_interface.h
/usr/include/../lib/erlang/lib/erl_interface-3.7.7/include/erl_interface.h