Rename TARGET_OS_* to HOST_OS_*.

runtime/vm/os_thread.h

 // Copyright (c) 2012, 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.
 
 #ifndef RUNTIME_VM_OS_THREAD_H_
 #define RUNTIME_VM_OS_THREAD_H_
 
 #include "platform/globals.h"
 #include "vm/allocation.h"
 #include "vm/globals.h"
 
 // Declare the OS-specific types ahead of defining the generic classes.
-#if defined(TARGET_OS_ANDROID)
+#if defined(HOST_OS_ANDROID)
 #include "vm/os_thread_android.h"
-#elif defined(TARGET_OS_FUCHSIA)
+#elif defined(HOST_OS_FUCHSIA)
 #include "vm/os_thread_fuchsia.h"
-#elif defined(TARGET_OS_LINUX)
+#elif defined(HOST_OS_LINUX)
 #include "vm/os_thread_linux.h"
-#elif defined(TARGET_OS_MACOS)
+#elif defined(HOST_OS_MACOS)
 #include "vm/os_thread_macos.h"
-#elif defined(TARGET_OS_WINDOWS)
+#elif defined(HOST_OS_WINDOWS)
 #include "vm/os_thread_win.h"
 #else
 #error Unknown target os.
 #endif
 
 namespace dart {
 
 // Forward declarations.
 class Log;
 class Mutex;
@@ skipping 321 matching lines @@
   friend class SafepointMonitorLocker;
   friend void Dart_TestMonitor();
   DISALLOW_COPY_AND_ASSIGN(Monitor);
 };
 
 
 }  // namespace dart
 
 
 #endif  // RUNTIME_VM_OS_THREAD_H_