Don't rely on `touch' being available (windows ninja)

pylib/gyp/generator/ninja.py

 # 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.
 
 import copy
 import gyp
 import gyp.common
 import gyp.msvs_emulation
 import gyp.system_test
 import gyp.xcode_emulation
@@ skipping 1176 matching lines @@
                'plutil -convert xml1 $out $out'))
     master_ninja.rule(
       'mac_tool',
       description='MACTOOL $mactool_cmd $in',
       command='$env $mac_tool $mactool_cmd $in $out')
     master_ninja.rule(
       'package_framework',
       description='PACKAGE FRAMEWORK $out, POSTBUILDS',
       command='$mac_tool package-framework $out $version$postbuilds '
               '&& touch $out')
-  master_ninja.rule(
-    'stamp',
-    description='STAMP $out',
-    command='${postbuilds}touch $out')
   if flavor == 'win':
+    master_ninja.rule(
+      'stamp',
+      description='STAMP $out',
+      command='cmd /c copy /y nul $out>nul')
     # TODO(scottmg): Copy fallback?
     master_ninja.rule(
       'copy',
       description='COPY $in $out',
       command='cmd /c mklink /h $out $in >nul || mklink /h /j $out $in >nul')
   else:
     master_ninja.rule(
+      'stamp',
+      description='STAMP $out',
+      command='${postbuilds}touch $out')
+    master_ninja.rule(
       'copy',
       description='COPY $in $out',
       command='ln -f $in $out 2>/dev/null || (rm -rf $out && cp -af $in $out)')
   master_ninja.newline()
 
   all_targets = set()
   for build_file in params['build_files']:
     for target in gyp.common.AllTargets(target_list, target_dicts, build_file):
       all_targets.add(target)
   all_outputs = set()
@@ skipping 45 matching lines @@
 
   user_config = params.get('generator_flags', {}).get('config', None)
   if user_config:
     GenerateOutputForConfig(target_list, target_dicts, data, params,
                             user_config)
   else:
     config_names = target_dicts[target_list[0]]['configurations'].keys()
     for config_name in config_names:
       GenerateOutputForConfig(target_list, target_dicts, data, params,
                               config_name)