Log TLS handshake result

Makes it easier to debug TLS issues, and to see the effect of
altering the priority string.
diff --git a/common/rfb/CSecurityTLS.cxx b/common/rfb/CSecurityTLS.cxx
index e1a31f7..000331c 100644
--- a/common/rfb/CSecurityTLS.cxx
+++ b/common/rfb/CSecurityTLS.cxx
@@ -196,6 +196,9 @@
     throw AuthFailureException("TLS Handshake failed");
   }
 
+  vlog.debug("TLS handshake completed with %s",
+             gnutls_session_get_desc(session));
+
   checkSession();
 
   cc->setStreams(tlsis, tlsos);
diff --git a/common/rfb/SSecurityTLS.cxx b/common/rfb/SSecurityTLS.cxx
index 49532f5..d5ef47e 100644
--- a/common/rfb/SSecurityTLS.cxx
+++ b/common/rfb/SSecurityTLS.cxx
@@ -163,7 +163,8 @@
     throw AuthFailureException("TLS Handshake failed");
   }
 
-  vlog.debug("Handshake completed");
+  vlog.debug("TLS handshake completed with %s",
+             gnutls_session_get_desc(session));
 
   sc->setStreams(tlsis, tlsos);