Superficial gyp changes to not immediately error out on Windows

tools/tools.gyp

 # Copyright 2014 The Crashpad Authors. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
 #     http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 54 matching lines @@
       'type': 'executable',
       'dependencies': [
         'tool_support',
         '../compat/compat.gyp:compat',
         '../third_party/mini_chromium/mini_chromium/base/base.gyp:base',
         '../util/util.gyp:util',
       ],
       'include_dirs': [
         '..',
       ],
-      'link_settings': {
-        'libraries': [
-          '$(SDKROOT)/System/Library/Frameworks/CoreFoundation.framework',
-          '$(SDKROOT)/System/Library/Frameworks/Foundation.framework',
-        ],
-      },
+      'conditions': [

[Mark Mentovai, 2014/09/30 19:55:01]

None of these tools make any sense off of Mac. We should just move all three
tools into a Mac-only condition.

[scottmg, 2014/09/30 19:59:49]

Done.

+        ['OS=="mac"', {
+          'link_settings': {
+            'libraries': [
+              '$(SDKROOT)/System/Library/Frameworks/CoreFoundation.framework',
+              '$(SDKROOT)/System/Library/Frameworks/Foundation.framework',
+            ],
+          },
+        }],
+      ],
       'sources': [
         'on_demand_service_tool.mm',
       ],
     },
   ],
 }