Use sse4.2 CRC32 instructions to hash when available.

gyp/core.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.
 # Include this gypi to include all 'core' files
 # The parent gyp/gypi file must define
 #       'skia_src_path'     e.g. skia/trunk/src
 #       'skia_include_path' e.g. skia/trunk/include
 #
 # The skia build defines these in common_variables.gypi
@@ skipping 47 matching lines @@
         '<(skia_src_path)/core/SkBlitter.cpp',
         '<(skia_src_path)/core/SkBlitter_A8.cpp',
         '<(skia_src_path)/core/SkBlitter_ARGB32.cpp',
         '<(skia_src_path)/core/SkBlitter_PM4f.cpp',
         '<(skia_src_path)/core/SkBlitter_RGB16.cpp',
         '<(skia_src_path)/core/SkBlitter_Sprite.cpp',
         '<(skia_src_path)/core/SkBuffer.cpp',
         '<(skia_src_path)/core/SkCachedData.cpp',
         '<(skia_src_path)/core/SkCanvas.cpp',
         '<(skia_src_path)/core/SkCanvasPriv.h',
-        '<(skia_src_path)/core/SkChecksum.cpp',
         '<(skia_src_path)/core/SkChunkAlloc.cpp',
         '<(skia_src_path)/core/SkClipStack.cpp',
         '<(skia_src_path)/core/SkColor.cpp',
         '<(skia_src_path)/core/SkColorFilter.cpp',
         '<(skia_src_path)/core/SkColorFilterShader.cpp',
         '<(skia_src_path)/core/SkColorMatrixFilterRowMajor255.cpp',
         '<(skia_src_path)/core/SkColorMatrixFilterRowMajor255.h',
         '<(skia_src_path)/core/SkColorShader.cpp',
         '<(skia_src_path)/core/SkColorShader.h',
         '<(skia_src_path)/core/SkColorSpace.cpp',
@@ skipping 428 matching lines @@
         '<(skia_src_path)/pathops/SkPathOpsLine.h',
         '<(skia_src_path)/pathops/SkPathOpsPoint.h',
         '<(skia_src_path)/pathops/SkPathOpsQuad.h',
         '<(skia_src_path)/pathops/SkPathOpsRect.h',
         '<(skia_src_path)/pathops/SkPathOpsTSect.h',
         '<(skia_src_path)/pathops/SkPathOpsTypes.h',
         '<(skia_src_path)/pathops/SkPathWriter.h',
         '<(skia_src_path)/pathops/SkReduceOrder.h',
     ],
 }