remove U16 support, just support F16

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 300 matching lines @@
         '<(skia_src_path)/core/SkUtils.h',
         '<(skia_src_path)/core/SkValidatingReadBuffer.cpp',
         '<(skia_src_path)/core/SkValidatingReadBuffer.h',
         '<(skia_src_path)/core/SkValidationUtils.h',
         '<(skia_src_path)/core/SkVarAlloc.cpp',
         '<(skia_src_path)/core/SkVertState.cpp',
         '<(skia_src_path)/core/SkWriteBuffer.cpp',
         '<(skia_src_path)/core/SkWriter32.cpp',
         '<(skia_src_path)/core/SkXfermode.cpp',
         '<(skia_src_path)/core/SkXfermode4f.cpp',
-        '<(skia_src_path)/core/SkXfermodeU64.cpp',
+        '<(skia_src_path)/core/SkXfermodeF16.cpp',
         '<(skia_src_path)/core/SkXfermode_proccoeff.h',
         '<(skia_src_path)/core/SkXfermodeInterpretation.cpp',
         '<(skia_src_path)/core/SkXfermodeInterpretation.h',
         '<(skia_src_path)/core/SkYUVPlanesCache.cpp',
         '<(skia_src_path)/core/SkYUVPlanesCache.h',
 
         '<(skia_src_path)/image/SkImage.cpp',
         '<(skia_src_path)/image/SkImage_Generator.cpp',
 #        '<(skia_src_path)/image/SkImage_Gpu.cpp',
         '<(skia_src_path)/image/SkImage_Raster.cpp',
@@ skipping 153 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',
     ],
 }