Revert of Treat std::atomic_int as a trivial class member when checking for non-trivial classes.

tools/clang/plugins/tests/trivial_ctor.h

-// Copyright (c) 2016 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 TRIVIAL_CTOR_H_
-#define TRIVIAL_CTOR_H_
-
-template<typename T>
-struct atomic {
-/*
-  atomic() noexcept = default;
-  ~atomic() noexcept = default;
-  atomic(const atomic&) = delete;
-  atomic& operator=(const atomic&) = delete;
-  atomic& operator=(const atomic&) volatile = delete;
-
-  constexpr atomic(T i) noexcept : i(i) { }
-*/
-
-  T i;
-};
-
-typedef atomic<int> atomic_int;
-
-struct MySpinLock {
-  MySpinLock();
-  ~MySpinLock();
-  MySpinLock(const MySpinLock&);
-  MySpinLock(MySpinLock&&);
-  atomic_int lock_;
-};
-
-#endif  // TRIVIAL_CTOR_H_