Fix issue 108 - provide a more detailed socket error code. Based on the patch  attached to that issue provided by Bert.
Fix issue 108 - provide a more detailed socket error code. Based on the patch 
attached to that issue provided by Bert.

* outgoing.c
  (serf__process_connection): When possible get a the last error from the socket
       using the platform's socket API.

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