Move sync code to include/, switch from using platform define to a proxy header in core/

gyp/tools.gyp

     # GYP file to build various tools.
 #
 # To build on Linux:
 #  ./gyp_skia tools.gyp && make tools
 #
 {
   'includes': [
     'apptype_console.gypi',
   ],
   'targets': [
@@ skipping 589 matching lines @@
           '<(skia_include_path)/pdf',
           '<(skia_include_path)/pipe',
           '<(skia_include_path)/ports',
           '<(skia_include_path)/svg',
           '<(skia_include_path)/utils',
           '<(skia_include_path)/views',
           '<(skia_include_path)/xml',
         ],
         'paths_to_ignore': [
           '<(skia_include_path)/gpu/gl/GrGLConfig_chrome.h',
+          '<(skia_include_path)/ports/SkAtomics_sync.h',
+          '<(skia_include_path)/ports/SkAtomics_win.h',
+          '<(skia_include_path)/ports/SkBarriers_arm.h',
+          '<(skia_include_path)/ports/SkBarriers_tsan.h',
+          '<(skia_include_path)/ports/SkBarriers_x86.h',
+          '<(skia_include_path)/ports/SkMutex_pthread.h',
+          '<(skia_include_path)/ports/SkMutex_win.h',
           '<(skia_include_path)/ports/SkTypeface_mac.h',
           '<(skia_include_path)/ports/SkTypeface_win.h',
           '<(skia_include_path)/utils/ios',
           '<(skia_include_path)/utils/mac',
           '<(skia_include_path)/utils/win',
           '<(skia_include_path)/utils/SkDebugUtils.h',
           '<(skia_include_path)/utils/SkJSONCPP.h',
           '<(skia_include_path)/views/animated',
           '<(skia_include_path)/views/SkOSWindow_Android.h',
           '<(skia_include_path)/views/SkOSWindow_iOS.h',
@@ skipping 115 matching lines @@
               'flags.gyp:flags',
               'skia_lib.gyp:skia_lib',
               'resources',
             ],
           },
         ],
       },
     ],
   ],
 }