Fix MinGW-w64 compilation

src/platform-win32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 94 matching lines @@
       --dest_size;
       --count;
     }
   }
   CHECK_GT(dest_size, 0);
   *dest = 0;
   return 0;
 }
 
 
+#ifndef __MINGW64_VERSION_MAJOR
+
 inline void MemoryBarrier() {
   int barrier = 0;
   __asm__ __volatile__("xchgl %%eax,%0 ":"=r" (barrier));
 }
 
+#endif  // __MINGW64_VERSION_MAJOR
+
+
 #endif  // __MINGW32__
 
 // Generate a pseudo-random number in the range 0-2^31-1. Usually
 // defined in stdlib.h. Missing in both Microsoft Visual Studio C++ and MinGW.
 int random() {
   return rand();
 }
 
 
 namespace v8 {
@@ skipping 1938 matching lines @@
 
 
 void Sampler::Stop() {
   ASSERT(IsActive());
   SamplerThread::RemoveActiveSampler(this);
   SetActive(false);
 }
 
 
 } }  // namespace v8::internal