Tidy up the http state machine a bit. Make sure that http_nextstate() runs

Tidy up the http state machine a bit. Make sure that http_nextstate() runs
until an error or an IO opperation is needed. In other words it should not
return 0. Because of this adjust the http_tls_connect() call a bit. Also
call http_connect() in http_redirect() instead of needing an extra step
in the state machine. Last but not least make sure that http_handle() does
only one IO operation and check for possible POLLHUP event.
OK tb@