Add support for building the Dart VM for Android OS.

runtime/platform/utils_android.h

Index: runtime/platform/utils_android.h
diff --git a/runtime/platform/utils_linux.h b/runtime/platform/utils_android.h
similarity index 82%
copy from runtime/platform/utils_linux.h
copy to runtime/platform/utils_android.h
index 6cfc32f5a2e10707b603f884e39f74f3b9810e46..23c69c4a15ef8ca300d6889c856dc2dc46a061ac 100644
--- a/runtime/platform/utils_linux.h
+++ b/runtime/platform/utils_android.h
@@ -2,8 +2,8 @@
 // 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 PLATFORM_UTILS_LINUX_H_
-#define PLATFORM_UTILS_LINUX_H_
+#ifndef PLATFORM_UTILS_ANDROID_H_
+#define PLATFORM_UTILS_ANDROID_H_
 
 namespace dart {
 
@@ -19,4 +19,4 @@ inline int Utils::CountTrailingZeros(uword x) {
 
 }  // namespace dart
 
-#endif  // PLATFORM_UTILS_LINUX_H_
+#endif  // PLATFORM_UTILS_ANDROID_H_