srv_echo: clarification regarding is_eof vs echo_data->eof in echo_io()

[tomers]

Hi Christos,

I got a question regarding srv_echo. In echo_io, theres an iseof argument, which according to documentation, "It has non zero value if the data in rbuf buffer are the last data from the ICAP client". But also there's echo_data->eof which is set by echo_end_of_data_handler, which is "called if we returned CI_MOD_CONTINUE in echo_check_preview_handler
function, after we read all the data from the ICAP client".

So my question is whether we really need that flag in echo_data, the service data struct. Maybe we can just regard iseof in echo_io? Currently this parameter is ignored.

Whatever the answer is, I think that we should add some comment in the code of echo_io to clarify this issue, as I am sure every new comer to this code might ask it.