Creating a new wrapper for gif decoder

gyp/giflib.gyp

Index: gyp/giflib.gyp
diff --git a/gyp/giflib.gyp b/gyp/giflib.gyp
index 57b3c276546e0890403be73b957304e91fdde2c5..e9d990565b6d8deae257aa9d23dc9243da6fe677 100644
--- a/gyp/giflib.gyp
+++ b/gyp/giflib.gyp
@@ -14,9 +14,6 @@
         [ 'skia_android_framework == 0',
           {
             'type': 'static_library',
-            'defines': [
-              'HAVE_CONFIG_H',
-            ],
             'include_dirs': [
               '../third_party/externals/giflib',
             ],
@@ -35,11 +32,27 @@
                 '-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': {