http: replace EVHTTP_REQ_UNKNOWN_ with 0 From the server perspective the evhttp_response_phrase_internal() should not be called with 0 before this patch, it will be called with EVHTTP_REQ_UNKNOWN_ hence this patch should not change behavior. Fixes: 68eb526d7b ("http: add WebDAV methods support") Fixes: #789 Fixes: #796 Reported-by: Thomas Bernard <miniupnp@free.fr>