Move utils.h and utils.cc from runtime/vm to runtime/platform

runtime/platform/utils.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 VM_UTILS_H_
-#define VM_UTILS_H_
+#ifndef PLATFORM_UTILS_H_
+#define PLATFORM_UTILS_H_
 
 #include "platform/assert.h"
-#include "vm/globals.h"
+#include "platform/globals.h"
 
 namespace dart {
 
 class Utils {
  public:
   template<typename T>
   static inline T Minimum(T x, T y) {
     return x < y ? x : y;
   }
 
@@ skipping 125 matching lines @@
 
   static char IntToHexDigit(int i) {
     ASSERT(0 <= i && i < 16);
     if (i < 10) return static_cast<char>('0' + i);
     return static_cast<char>('A' + (i - 10));
   }
 };
 
 }  // namespace dart
 
-#endif  // VM_UTILS_H_
+#endif  // PLATFORM_UTILS_H_