message: Fixes a "pure virtual method called" in proxy_protocol_test
diff: @@ -184,6 +184,7 @@ public:
  Stats::TestUtil::TestStore stats_store_;
  Api::ApiPtr api_;
  + BasicResourceLimitImpl open_connections_;
  Event::DispatcherPtr dispatcher_;
  std::shared_ptr<Network::TcpListenSocket> socket_;
  Network::MockListenSocketFactory socket_factory_;
  @@ -194,7 +195,6 @@ public:
  NiceMock<Network::MockConnectionCallbacks> connection_callbacks_;
  Network::Connection* server_connection_;
  Network::MockConnectionCallbacks server_callbacks_;
  - BasicResourceLimitImpl open_connections_;
  std::shared_ptr<Network::MockReadFilter> read_filter_;
  std::string name_;
  Api::OsSysCallsImpl os_sys_calls_actual_;
  