BUILD: ssl: OpenSSL 0.9.6 has no renegociation

It did not build anymore on 0.9.6. Not very important but better fix it.
diff --git a/src/ssl_sock.c b/src/ssl_sock.c
index f6c410f..2892f8f 100644
--- a/src/ssl_sock.c
+++ b/src/ssl_sock.c
@@ -467,6 +467,7 @@
 
 #ifndef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION   /* needs OpenSSL >= 0.9.7 */
 #define SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION 0
+#define SSL_renegotiate_pending(arg) 0
 #endif
 #ifndef SSL_OP_SINGLE_ECDH_USE                          /* needs OpenSSL >= 0.9.8 */
 #define SSL_OP_SINGLE_ECDH_USE 0