ninja windows: make sure that .s files aren't passed to compiler

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.MSVSVersion
 import gyp.system_test
@@ skipping 698 matching lines @@
       self.WriteVariableList('cflags_objcc', map(self.ExpandSpecial,
                                                  cflags_objcc))
     self.ninja.newline()
     outputs = []
     for source in sources:
       filename, ext = os.path.splitext(source)
       ext = ext[1:]
       obj_ext = self.obj_ext
       if ext in ('cc', 'cpp', 'cxx'):
         command = 'cxx'
-      elif ext in ('c', 's', 'S'):
+      elif ext == 'c' or (ext in ('s', 'S') and self.flavor != 'win'):
+        # TODO(scottmg): .s files won't be handled by the Windows compiler.
+        # We could add support for .asm, though that's only supported on
+        # x86. Currently not used in Chromium in favor of other third-party
+        # assemblers.
         command = 'cc'
       elif self.flavor == 'mac' and ext == 'm':
         command = 'objc'
       elif self.flavor == 'mac' and ext == 'mm':
         command = 'objcxx'
       elif self.flavor == 'win' and ext == 'rc':
         command = 'rc'
         obj_ext = '.res'
       else:
         # Ignore unhandled extensions.
@@ skipping 742 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)