/usr/lib/libei.a is in erlang-dev 1:16.b.3-dfsg-1ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/erlang/lib/erl_interface-3.7.15/lib/libei.a
/usr/lib/erlang/lib/erl_interface-3.7.15/lib/libei.a