Creating a new wrapper for gif decoder

gyp/giflib.gyp

 # Copyright 2014 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'variables': {
     'skia_warnings_as_errors': 0,
   },
   'targets': [
     {
       'target_name': 'giflib',
       'conditions': [
         [ 'skia_android_framework == 0',
           {
             'type': 'static_library',
-            'defines': [
-              'HAVE_CONFIG_H',
-            ],
             'include_dirs': [
               '../third_party/externals/giflib',
             ],
             'dependencies': [
             ],
             'direct_dependent_settings': {
               'include_dirs': [
                 '../third_party/externals/giflib',
               ],
             },
             'cflags': [
               '-w',
             ],
             'xcode_settings': {
               'WARNING_CFLAGS': [
                 '-w'
               ],
             },
+            'msvs_settings': {
+              'VCCLCompilerTool': {
+                'AdditionalOptions': [
+                  '/w',
+                ],
+              },
+            },
             'sources': [
               '../third_party/externals/giflib/dgif_lib.c',
               '../third_party/externals/giflib/gifalloc.c',
               '../third_party/externals/giflib/gif_err.c',
             ],
+            'conditions' : [
+              [ 'skia_os == "win"', {
+                  'include_dirs': [
+                    # Used to include a dummy unistd.h file for windows
+                    '../third_party/giflib',
+                  ],
+                },
+              ],
+            ],
           }, { # skia_android_framework
             'type': 'none',
             'direct_dependent_settings': {
               'libraries' : [
                 'libgif.a',
               ],
               'include_dirs': [
                 'external/giflib',
               ]
             }
           }
         ]
       ]
     }
   ]
 }