Make experimental/gc compilable on Mac OS.

src/platform-linux.cc

 // Copyright 2011 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 598 matching lines @@
 
 
 VirtualMemory::VirtualMemory(size_t size) {
   address_ = ReserveRegion(size);
   size_ = size;
 }
 
 
 VirtualMemory::~VirtualMemory() {
   if (IsReserved()) {
-    if (0 == munmap(address(), size())) address_ = NULL;
+    if (ReleaseRegion(address(), size())) address_ = NULL;
   }
 }
 
 
 bool VirtualMemory::IsReserved() {
   return address_ != NULL;
 }
 
 
 bool VirtualMemory::Commit(void* address, size_t size, bool is_executable) {
@@ skipping 547 matching lines @@
 
 
 void Sampler::Stop() {
   ASSERT(IsActive());
   SignalSender::RemoveActiveSampler(this);
   SetActive(false);
 }
 
 
 } }  // namespace v8::internal