Avoid segfault when resetting a connection due to (authentication) error.
Avoid segfault when resetting a connection due to (authentication) error.

* context.c
  (serf_event_trigger): If the connection was reset due to an error, the
   socket is already removed from the pollset and cleared so do not try
   to do that again here.
   TODO: use remove_connection from outgoing.c.


git-svn-id: 683495cb1553624b05a54e2ba9533425f69cf277@1303 61a7d7f5-40b7-0310-9c16-bb0ea8cb1845

coapp-packages/serf,coapp-packages/serf,coapp-packages/serf