[dart:io] Build fixes for Namespaces

runtime/bin/namespace_linux.cc

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
 #if defined(HOST_OS_LINUX)
 
 #include "bin/namespace.h"
 
 #include <errno.h>
 #include <fcntl.h>
 
 #include "bin/fdutils.h"
 #include "bin/file.h"
 #include "platform/signal_blocker.h"
 
 namespace dart {
 namespace bin {
 
 Namespace* Namespace::Create(const char* path) {
-  const intptr_t fd = TEMP_FAILURE_RETRY(open64(path, O_PATH));
+  const intptr_t fd = TEMP_FAILURE_RETRY(open64(path, O_DIRECTORY));
   if (fd < 0) {
     return NULL;
   }
   return new Namespace(fd);
 }
 
 Namespace::~Namespace() {
   if (namespc_ != kNone) {
     VOID_TEMP_FAILURE_RETRY(close(namespc_));
   }
@@ skipping 62 matching lines @@
 NamespaceScope::~NamespaceScope() {
   if (owns_fd_) {
     FDUtils::SaveErrorAndClose(fd_);
   }
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(HOST_OS_LINUX)