term_to_binary doesn't support lambdas

Following code:
```erl
-module(hello_world).
-export([f/0, start/0]).

f() ->
    term_to_binary(fun() -> ok end).

start() ->
    ?MODULE:f(),
    ok.
```

crashes with
```
Unknown external term type: 106583908418080
```

Using external functions (`term_to_binary(fun ?MODULE:f/0)`) works.