Don't overwrite stacktrace in `cowboy_rest:error_terminate/2`
Don't overwrite stacktrace in `cowboy_rest:error_terminate/2`

This stacktrace is very useful in the `onresponse` hook. For example:

```erlang
internal_error_hook(500, Headers, <<>>, Req) ->
    StackTrace = erlang:get_stacktrace(),
    Headers0 = [{N, V} || {N, V} <- Headers, N =/= <<"content-length">>],
    Body = io_lib:format("~p", [StackTrace]),
    {ok, Req0} = cowboy_req:reply(500, Headers0, Body, Req),
    Req0;
internal_error_hook(Status, Headers, Body, Req) ->
    {ok, Req0} = cowboy_req:reply(Status, Headers, Body, Req),
    Req0.
```

bsmr-erlang/cowboy,hairyhum/cowboy,CrankWheel/cowboy,binarin/cowboy,nviennot/cowboy,manastech/cowboy,turtleDeng/cowboy,kivra/cowboy,noname007/cowboy,layerhq/cowboy,MSch/cowboy,K2InformaticsGmbH/cowboy,unisontech/cowboy,linearregression/cowboyku,acrispin/cowboy,cad627/cowboy,276361270/cowboy,manastech/cowboy,heroku/cowboy,pap/cowboy,dangjun625/cowboy,Reimerei/cowboy,LineMetrics/cowboy,yangchengjian/cowboy,rbalint/pkg-erlang-cowboy,sile/cowboy,imdeps/cowboy,cad627/cowboy,omusico/cowboy,heroku/cowboyku,paulperegud/cowboy,lpgauth/cowboy,grahamrhay/cowboy,callsign-core/cowboy_hybi00,layerhq/cowboy,essen/cowboy,unisontech/cowboy,yangchengjian/cowboy,venkateshreddy/cowboy,essen/cowboy,bobos/ecweb,LineMetrics/cowboy,heroku/cowboy,lpgauth/cowboy,ninenines/cowboy,ferd/cowboyku,rabbitmq/cowboy,binarin/cowboy,callsign-core/cowboy_hybi00,LineMetrics/cowboy,odo/cowboy