Add blimp to root GN check_targets

blimp/client/app/blimp_startup.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BLIMP_CLIENT_APP_BLIMP_STARTUP_H_
 #define BLIMP_CLIENT_APP_BLIMP_STARTUP_H_
 
-#include "blimp/client/blimp_client_export.h"
-
 namespace blimp {
 namespace client {
 
-BLIMP_CLIENT_EXPORT void InitializeLogging();
+void InitializeLogging();
 
-BLIMP_CLIENT_EXPORT bool InitializeMainMessageLoop();
+bool InitializeMainMessageLoop();
 
 }  // namespace client
 }  // namespace blimp
 
 #endif  // BLIMP_CLIENT_APP_BLIMP_STARTUP_H_