Fix compilation with recent MinGW64 versions.

src/gdb-jit.cc

 // Copyright 2010 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 1854 matching lines @@
 
 
 static void DestroyCodeEntry(JITCodeEntry* entry) {
   free(entry);
 }
 
 
 static void RegisterCodeEntry(JITCodeEntry* entry,
                               bool dump_if_enabled,
                               const char* name_hint) {
-#if defined(DEBUG) && !defined(WIN32)
+#if defined(DEBUG) && !V8_OS_WIN
   static int file_num = 0;
   if (FLAG_gdbjit_dump && dump_if_enabled) {
     static const int kMaxFileNameSize = 64;
     static const char* kElfFilePrefix = "/tmp/elfdump";
     static const char* kObjFileExt = ".o";
     char file_name[64];
 
     OS::SNPrintF(Vector<char>(file_name, kMaxFileNameSize),
                  "%s%s%d%s",
                  kElfFilePrefix,
@@ skipping 304 matching lines @@
   ScopedLock lock(mutex.Pointer());
   ASSERT(!IsLineInfoTagged(line_info));
   HashMap::Entry* e = GetEntries()->Lookup(code, HashForCodeObject(code), true);
   ASSERT(e->value == NULL);
   e->value = TagLineInfo(line_info);
 }
 
 
 } }  // namespace v8::internal
 #endif