Don't duplicate OS::CpuFeaturesImpliedByPlatform 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 37 matching lines @@
 #include "vm-state-inl.h"
 #include "win32-headers.h"
 
 namespace v8 {
 namespace internal {
 
 
 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
   // that requires 16 byte alignment such as movdqa on x86.
   return 16;
 }
 
 
 const char* OS::LocalTimezone(double time) {
   if (std::isnan(time)) return "";
   time_t tv = static_cast<time_t>(floor(time/msPerSecond));
@@ skipping 413 matching lines @@
   limit_mutex = CreateMutex();
 }
 
 
 void OS::TearDown() {
   delete limit_mutex;
 }
 
 
 } }  // namespace v8::internal