Move NumberOfProcessorsOnline from CPU to OS

src/platform.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This module contains the platform-specific code. This make the rest of the
 // code less dependent on operating system, compilers and runtime libraries.
 // This module does specifically not deal with differences between different
 // processor architecture.
 // The platform classes have the same definition for all platforms. The
 // implementation for a particular platform is put in platform_<os>.cc.
@@ skipping 256 matching lines @@
   // using --never-compact) if accurate profiling is desired.
   static void SignalCodeMovingGC();
 
   // The return value indicates the CPU features we are sure of because of the
   // OS.
   // This is a little messy because the interpretation is subject to the cross
   // of the CPU and the OS.  The bits in the answer correspond to the bit
   // positions indicated by the members of the CpuFeature enum from globals.h
   static unsigned CpuFeaturesImpliedByPlatform();
 
+  // Returns the number of processors online.
+  static int NumberOfProcessorsOnline();
+
   // The total amount of physical memory available on the current system.
   static uint64_t TotalPhysicalMemory();
 
   // Maximum size of the virtual memory.  0 means there is no artificial
   // limit.
   static intptr_t MaxVirtualMemory();
 
   // Returns the double constant NAN
   static double nan_value();
 
@@ skipping 297 matching lines @@
   char name_[kMaxThreadNameLength];
   int stack_size_;
   Semaphore* start_semaphore_;
 
   DISALLOW_COPY_AND_ASSIGN(Thread);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_PLATFORM_H_