Fix build with old c++

Author: proller

lib/cpp/src/thrift/transport/TSocketPool.cpp

@@ -189,9 +189,13 @@ void TSocketPool::open() {
  }
 
  if (randomize_ && numServers > 1) {
+#if __cplusplus >= 201500L // c++17
  std::random_device rng;
  std::mt19937 urng(rng());
  std::shuffle(servers_.begin(), servers_.end(), urng);
+#else
+ std::random_shuffle(servers_.begin(), servers_.end());
+#endif
  }
 
  for (size_t i = 0; i < numServers; ++i) {