Make the ninja pool math correct.

pylib/gyp/generator/ninja.py

 # Copyright (c) 2013 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import copy
 import hashlib
 import multiprocessing
 import os.path
 import re
 import signal
@@ skipping 1343 matching lines @@
         ("ullAvailPageFile", ctypes.c_ulonglong),
         ("ullTotalVirtual", ctypes.c_ulonglong),
         ("ullAvailVirtual", ctypes.c_ulonglong),
         ("sullAvailExtendedVirtual", ctypes.c_ulonglong),
       ]
 
     stat = MEMORYSTATUSEX()
     stat.dwLength = ctypes.sizeof(stat)
     ctypes.windll.kernel32.GlobalMemoryStatusEx(ctypes.byref(stat))
 
-    return max(1, stat.ullTotalPhys / (4 ** 31))
+    return max(1, stat.ullTotalPhys / (4 * (2 ** 30)))  # total / 4GB
   else:
     # TODO(scottmg): Implement this for other platforms.
     return 1
 
 
 def GenerateOutputForConfig(target_list, target_dicts, data, params,
                             config_name):
   options = params['options']
   flavor = gyp.common.GetFlavor(params)
   generator_flags = params.get('generator_flags', {})
@@ skipping 496 matching lines @@
           arglists.append(
               (target_list, target_dicts, data, params, config_name))
         pool.map(CallGenerateOutputForConfig, arglists)
       except KeyboardInterrupt, e:
         pool.terminate()
         raise e
     else:
       for config_name in config_names:
         GenerateOutputForConfig(target_list, target_dicts, data, params,
                                 config_name)