use new perf proto options in c++
diff --git a/test/cpp/qps/server_sync.cc b/test/cpp/qps/server_sync.cc
index a09b174..3a15bec 100644
--- a/test/cpp/qps/server_sync.cc
+++ b/test/cpp/qps/server_sync.cc
@@ -89,7 +89,7 @@
 
     char* server_address = NULL;
 
-    gpr_join_host_port(&server_address, "::", port());
+    gpr_join_host_port(&server_address, config.host().c_str(), port());
     builder.AddListeningPort(server_address,
                              Server::CreateServerCredentials(config));
     gpr_free(server_address);