Create SDL backed SkOSWindow

third_party/libsdl/sdl.gypi

 # Copyright 2015 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'targets': [
     {
       'target_name': 'sdl',
       'product_name': 'sdl',
-      'type': 'shared_library',
+      'type': 'static_library',
       'include_dirs': [
         '<(base_dir)/<(skia_os)',
         '<(src_dir)/include',
       ],
-      'includes': [
-        'sdl_sources.gypi',
-      ],
-      'sources': [
-        '<@(sdl_sources)',
-      ],
       'direct_dependent_settings': {
         'include_dirs': [
           '<(src_dir)/include',
         ]
       },
       'cflags': [
         '-g',
         '-w',
       ],
       'conditions': [
         ['skia_os == "linux"', {
           'includes': [
             'linux/sdl_linux.gypi',
           ]
         }],
       ],
     },
   ],
 }