Don't duplicate ceiling() for every POSIX platform.

src/platform-cygwin.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 34 matching lines @@
 #include "platform.h"
 #include "simulator.h"
 #include "v8threads.h"
 #include "vm-state-inl.h"
 #include "win32-headers.h"
 
 namespace v8 {
 namespace internal {
 
 
-double ceiling(double x) {
-  return ceil(x);
-}
-
-
 static Mutex* limit_mutex = NULL;
 
 
 uint64_t OS::CpuFeaturesImpliedByPlatform() {
   return 0;  // Nothing special about Cygwin.
 }
 
 
 int OS::ActivationFrameAlignment() {
   // With gcc 4.4 the tree vectorization optimizer can generate code
@@ skipping 421 matching lines @@
   limit_mutex = CreateMutex();
 }
 
 
 void OS::TearDown() {
   delete limit_mutex;
 }
 
 
 } }  // namespace v8::internal