Update libpng to 1.6.22beta

gyp/codec.gyp

 # Copyright 2015 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 # Copyright 2015 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # GYP file for codec project.
@@ skipping 30 matching lines @@
         '../src/codec/SkBmpStandardCodec.cpp',
         '../src/codec/SkCodec.cpp',
         '../src/codec/SkGifCodec.cpp',
         '../src/codec/SkIcoCodec.cpp',
         '../src/codec/SkJpegCodec.cpp',
         '../src/codec/SkJpegDecoderMgr.cpp',
         '../src/codec/SkJpegUtility_codec.cpp',
         '../src/codec/SkMaskSwizzler.cpp',
         '../src/codec/SkMasks.cpp',
         '../src/codec/SkPngCodec.cpp',
-        '../src/codec/SkPngFilters.cpp',
         '../src/codec/SkSampler.cpp',
         '../src/codec/SkSampledCodec.cpp',
         '../src/codec/SkSwizzler.cpp',
         '../src/codec/SkWbmpCodec.cpp',
         '../src/codec/SkWebpAdapterCodec.cpp',
         '../src/codec/SkWebpCodec.cpp',
 
         '../src/codec/SkCodecImageGenerator.cpp',
         '../src/ports/SkImageGenerator_skia.cpp',
       ],
@@ skipping 70 matching lines @@
         ['skia_os == "ios" or skia_os == "mac"', {
           'xcode_settings': {
             'OTHER_CFLAGS': ['-fexceptions'],
             'OTHER_CPLUSPLUSFLAGS': ['-fexceptions'],
           },
         }],
       ],
     },
   ],
 }