Move SkAtomics.h to private.

src/core/SkSharedMutex.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkSharedLock_DEFINED
 #define SkSharedLock_DEFINED
 
-#include "SkAtomics.h"
+#include "../private/SkAtomics.h"
 #include "SkSemaphore.h"
 #include "SkTypes.h"
 
 #ifdef SK_DEBUG
     #include "SkMutex.h"
     #include "../private/SkUniquePtr.h"
 #endif  // SK_DEBUG
 
 // There are two shared lock implementations one debug the other is high performance. They implement
 // an interface similar to pthread's rwlocks.
@@ skipping 41 matching lines @@
     SkSemaphore       fExclusiveQueue;
 #endif  // SK_DEBUG
 };
 
 #ifndef SK_DEBUG
 inline void SkSharedMutex::assertHeld() const {};
 inline void SkSharedMutex::assertHeldShared() const {};
 #endif  // SK_DEBUG
 
 #endif // SkSharedLock_DEFINED