TLS: new method to specify SSL/TLS version

SSL/TLS protocols only listed in ssl_protocols should be used.
The name "ssl_protocols" comes from nginx.

Resolves #428.

common/trans.c

@@ -882,7 +882,7 @@ trans_get_out_s(struct trans *self, int size)
 /* returns error */
 int APP_CC
 trans_set_tls_mode(struct trans *self, const char *key, const char *cert,
-                   int disableSSLv3, const char *tls_ciphers)
+                   long ssl_protocols, const char *tls_ciphers)
 {
     self->tls = ssl_tls_create(self, key, cert);
     if (self->tls == NULL)
@@ -891,7 +891,7 @@ trans_set_tls_mode(struct trans *self, const char *key, const char *cert,
         return 1;
     }
 
-    if (ssl_tls_accept(self->tls, disableSSLv3, tls_ciphers) != 0)
+    if (ssl_tls_accept(self->tls, ssl_protocols, tls_ciphers) != 0)
     {
         g_writeln("trans_set_tls_mode: ssl_tls_accept failed");
         return 1;