Fix compilation with recent MinGW64 versions.

src/ia32/regexp-macro-assembler-ia32.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 693 matching lines @@
   __ neg(ebx);
   if (mode_ == UC16) {
     __ lea(eax, Operand(edi, ebx, times_2, -char_size()));
   } else {
     __ lea(eax, Operand(edi, ebx, times_1, -char_size()));
   }
   // Store this value in a local variable, for use when clearing
   // position registers.
   __ mov(Operand(ebp, kInputStartMinusOne), eax);
 
-#ifdef WIN32
+#if V8_OS_WIN
   // Ensure that we write to each stack page, in order. Skipping a page
   // on Windows can cause segmentation faults. Assuming page size is 4k.
   const int kPageSize = 4096;
   const int kRegistersPerPage = kPageSize / kPointerSize;
   for (int i = num_saved_registers_ + kRegistersPerPage - 1;
       i < num_registers_;
       i += kRegistersPerPage) {
     __ mov(register_location(i), eax);  // One write every page.
   }
-#endif  // WIN32
+#endif  // V8_OS_WIN
 
   Label load_char_start_regexp, start_regexp;
   // Load newline if index is at start, previous character otherwise.
   __ cmp(Operand(ebp, kStartIndex), Immediate(0));
   __ j(not_equal, &load_char_start_regexp, Label::kNear);
   __ mov(current_character(), '\n');
   __ jmp(&start_regexp, Label::kNear);
 
   // Global regexp restarts matching here.
   __ bind(&load_char_start_regexp);
@@ skipping 588 matching lines @@
 }
 
 
 #undef __
 
 #endif  // V8_INTERPRETED_REGEXP
 
 }}  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32