Dirty workarounds to compile jiffy with Erlang/OTP 23 (#3282)

Works for me with:
./configure --disable-pam
./rebar get-deps
./rebar configure-deps
./rebar compile
make install

changes in erlang-native-compiler used by jiffy:

src/rebar_port_compiler.erl
-     {"ERL_LDFLAGS"  , " -L$ERL_EI_LIBDIR -lerl_interface -lei"},
+     {"ERL_LDFLAGS"  , " -L$ERL_EI_LIBDIR -lei"},

src/rebar_utils.erl
--dialyzer({no_missing_calls, escript_foldl/3}).

rebar.config

@@ -154,6 +154,9 @@
   {if_not_rebar3, {if_version_above, "22", {add, [{port_env, [{"ERL_LDFLAGS", " -L$ERL_EI_LIBDIR -lei"}]}]}}},
   {del, [{erl_opts, [warnings_as_errors]}]}]}.
 
+{post_hooks, [{'get-deps', "cp tools/enc deps/jiffy/"}]}.
+{post_hooks, [{'update-deps', "cp tools/enc deps/jiffy/"}]}.
+
 {post_hook_configure, [{"fast_tls", []},
                        {"stringprep", []},
                        {"fast_yaml", []},