Add support for asynchronous session lookup.

ssl/ssl_locl.h

diff --git a/ssl/ssl_locl.h b/ssl/ssl_locl.h
index cbfa172..91c8c1c 100644
--- a/ssl/ssl_locl.h
+++ b/ssl/ssl_locl.h
@@ -474,6 +474,8 @@
 #define CERT_PRIVATE_KEY	2
 */
 
+#define PENDING_SESSION -10000
+
 #ifndef OPENSSL_NO_EC
 /* From ECC-TLS draft, used in encoding the curve type in 
  * ECParameters