Rename TARGET_OS_* to HOST_OS_*.

runtime/platform/floating_point_win.cc

 // 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.
 
 #include "platform/globals.h"
-#if defined(TARGET_OS_WINDOWS)
+#if defined(HOST_OS_WINDOWS)
 
 #include "platform/floating_point_win.h"
 
 #include <limits>  // NOLINT
 
 // Taken from third_party/v8/src/platform-win32.cc
 double fmod_ieee(double x, double y) {
   // x is dividend, y is divisor.
   // Work around MS fmod bugs. ISO Standard says:
   // If dividend is finite and divisor is an infinity or
@@ skipping 22 matching lines @@
     int index_x = (cls_x & _FPCLASS_PINF) != 0 ? 0 : 1;
     int index_y = (cls_y & _FPCLASS_PINF) != 0 ? 0 : 1;
     static double atans_at_infinities[2][2] = {
         {atan2(1., 1.), atan2(1., -1.)}, {atan2(-1., 1.), atan2(-1., -1.)}};
     return atans_at_infinities[index_x][index_y];
   } else {
     return atan2(x, y);
   }
 }
 
-#endif  // defined(TARGET_OS_WINDOWS)
+#endif  // defined(HOST_OS_WINDOWS)