Fix 100% CPU usage with many pipelined requests.
Fix 100% CPU usage with many pipelined requests.

* outgoing.c
  (write_to_connection): Mark pollset as dirty if we reached probable 
   keep-alive limit.
  (read_from_connection): Mark pollset as dirty when completed_responses 
   is changed.

jandre/serf,jandre/serf,jandre/serf,jandre/serf