Rename TARGET_OS_* to HOST_OS_*.

runtime/vm/cpuid.cc

 // Copyright (c) 2014, 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 "vm/globals.h"
-#if !defined(TARGET_OS_MACOS)
+#if !defined(HOST_OS_MACOS)
 #include "vm/cpuid.h"
 
 #if defined(HOST_ARCH_IA32) || defined(HOST_ARCH_X64)
 // GetCpuId() on Windows, __get_cpuid() on Linux
-#if defined(TARGET_OS_WINDOWS)
+#if defined(HOST_OS_WINDOWS)
 #include <intrin.h>  // NOLINT
 #else
 #include <cpuid.h>  // NOLINT
 #endif
 #endif
 
 namespace dart {
 
 bool CpuId::sse2_ = false;
 bool CpuId::sse41_ = false;
 const char* CpuId::id_string_ = NULL;
 const char* CpuId::brand_string_ = NULL;
 
 #if defined(HOST_ARCH_IA32) || defined(HOST_ARCH_X64)
 
 void CpuId::GetCpuId(int32_t level, uint32_t info[4]) {
-#if defined(TARGET_OS_WINDOWS)
+#if defined(HOST_OS_WINDOWS)
   // The documentation for __cpuid is at:
   // http://msdn.microsoft.com/en-us/library/hskdteyh(v=vs.90).aspx
   __cpuid(reinterpret_cast<int*>(info), level);
 #else
   __get_cpuid(level, &info[0], &info[1], &info[2], &info[3]);
 #endif
 }
 
 
 void CpuId::InitOnce() {
@@ skipping 68 matching lines @@
     default: {
       UNREACHABLE();
       return NULL;
     }
   }
 }
 
 #endif  // defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64)
 }  // namespace dart
 
-#endif  // !defined(TARGET_OS_MACOS)
+#endif  // !defined(HOST_OS_MACOS)