Handle window chttpd small buffer test responses

On Windows it seems the sockets are closed and we get the `connection_closed`
error. Account for that error as well as a 400 or a `request_failed` response.

It behaves differently on Windows. At some point in the future investigate the
details but for now let's just bypass it.

src/chttpd/test/eunit/chttpd_socket_buffer_size_test.erl

@@ -51,15 +51,23 @@ small_recbuf(_, {_, Db}) ->
         ?_test(begin
             Id = data(2048),
             Response = put_req(url(Db) ++ "/" ++ Id, "{}"),
-            ?assert(Response =:= 400 orelse Response =:= request_failed)
+            ?assert(
+                Response =:= 400 orelse
+                    Response =:= request_failed orelse
+                    Response =:= connection_closed
+            )
         end)}.
 
 small_buffer(_, {_, Db}) ->
     {timeout, 30,
         ?_test(begin
             Id = data(2048),
             Response = put_req(url(Db) ++ "/" ++ Id, "{}"),
-            ?assert(Response =:= 400 orelse Response =:= request_failed)
+            ?assert(
+                Response =:= 400 orelse
+                    Response =:= request_failed orelse
+                    Response =:= connection_closed
+            )
         end)}.
 
 default_buffer(_, {_, Db}) ->