Revision 1717031

With the config store available we now have a location to store ssl session
state for resumption keyed by host+portnumber. Use this to optimize creating
additional ssl sessions (and in case of http/1.1 resetting connections),
within a single serf context.

* buckets/ssl_buckets.c
  (ssl_handshake): Check the config to see if we have a cached session.

* config_store.c
  (ssl_session_data): New struct.
  (SERF_CONFIG__SSL_SESSION): New config value.
  (serf__config_store_set_ssl_session,
   serf__config_store_get_ssl_session): New function.

* serf_private.h
  (serf__config_store_set_ssl_session,
   serf__config_store_get_ssl_session): New function.