Make header include guards great again

runtime/vm/bit_set.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_BIT_SET_H_
-#define VM_BIT_SET_H_
+#ifndef RUNTIME_VM_BIT_SET_H_
+#define RUNTIME_VM_BIT_SET_H_
 
 #include "platform/utils.h"
 #include "vm/globals.h"
 
 namespace dart {
 
 // Just like its namesake in the STL, a BitSet object contains a fixed
 // length sequence of bits.
 template<intptr_t N>
 class BitSet {
@@ skipping 76 matching lines @@
     return N;
   }
 
  private:
   static const int kLengthInWords = 1 + ((N - 1) / kBitsPerWord);
   uword data_[kLengthInWords];
 };
 
 }  // namespace dart
 
-#endif  // VM_BIT_SET_H_
+#endif  // RUNTIME_VM_BIT_SET_H_