Let relx know about application erl opts
Let relx know about application erl opts

This is so that some of them can be enforced
(such as warnings_as_errors) on relx's task like
generating a release or a release upgrade.

erlang/rebar3,lrascao/rebar3,rebar/rebar3,tsloughter/rebar3,saleyn/rebar3,rebar/rebar3,vladdu/rebar3,ferd/rebar3,djnym/rebar3