Fix header map nextPowerOf2 method.

pylib/gyp/mac_tool.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 """Utility functions to perform Xcode-style build steps.
 
 These functions are executed via gyp-mac-tool when using the Makefile generator.
 """
 
@@ skipping 621 matching lines @@
       for key, value in substitutions.iteritems():
         data = data.replace('$(%s)' % key, value)
       return data
     if isinstance(data, list):
       return [self._ExpandVariables(v, substitutions) for v in data]
     if isinstance(data, dict):
       return {k: self._ExpandVariables(data[k], substitutions) for k in data}
     return data
 
 def NextGreaterPowerOf2(x):
-  return 2**(x-1).bit_length()
+  return 2**(x).bit_length()
 
 def WriteHmap(output_name, filelist):
   """Generates a header map based on |filelist|.
 
   Per Mark Mentovai:
     A header map is structured essentially as a hash table, keyed by names used
     in #includes, and providing pathnames to the actual files.
 
   The implementation below and the comment above comes from inspecting:
     http://www.opensource.apple.com/source/distcc/distcc-2503/distcc_dist/include_server/headermap.py?txt
@@ skipping 46 matching lines @@
       out.write(struct.pack('<s', '\0'))
       base = os.path.dirname(path) + os.sep
       out.write(struct.pack('<%ds' % len(base), base))
       out.write(struct.pack('<s', '\0'))
       path = os.path.basename(path)
       out.write(struct.pack('<%ds' % len(path), path))
       out.write(struct.pack('<s', '\0'))
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))