remove dead header

gyp/effects.gypi

 # Include this gypi to include all 'effects' 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.
 #
 {
   'sources': [
     '<(skia_src_path)/effects/Sk1DPathEffect.cpp',
@@ skipping 68 matching lines @@
     '<(skia_src_path)/effects/gradients/SkTwoPointConicalGradient_gpu.cpp',
     '<(skia_src_path)/effects/gradients/SkTwoPointConicalGradient_gpu.h',
     '<(skia_src_path)/effects/gradients/SkSweepGradient.cpp',
     '<(skia_src_path)/effects/gradients/SkSweepGradient.h',
 
     '<(skia_include_path)/effects/Sk1DPathEffect.h',
     '<(skia_include_path)/effects/Sk2DPathEffect.h',
     '<(skia_include_path)/effects/SkXfermodeImageFilter.h',
     '<(skia_include_path)/effects/SkAlphaThresholdFilter.h',
     '<(skia_include_path)/effects/SkArithmeticMode.h',
-    '<(skia_include_path)/effects/SkAvoidXfermode.h',
     '<(skia_include_path)/effects/SkBitmapSource.h',
     '<(skia_include_path)/effects/SkBlurDrawLooper.h',
     '<(skia_include_path)/effects/SkBlurImageFilter.h',
     '<(skia_include_path)/effects/SkBlurMaskFilter.h',
     '<(skia_include_path)/effects/SkColorCubeFilter.h',
     '<(skia_include_path)/effects/SkColorMatrix.h',
     '<(skia_include_path)/effects/SkColorMatrixFilter.h',
     '<(skia_include_path)/effects/SkColorFilterImageFilter.h',
     '<(skia_include_path)/effects/SkCornerPathEffect.h',
     '<(skia_include_path)/effects/SkDashPathEffect.h',
@@ skipping 15 matching lines @@
     '<(skia_include_path)/effects/SkPixelXorXfermode.h',
     '<(skia_include_path)/effects/SkPorterDuff.h',
     '<(skia_include_path)/effects/SkRectShaderImageFilter.h',
     '<(skia_include_path)/effects/SkTableColorFilter.h',
     '<(skia_include_path)/effects/SkTableMaskFilter.h',
     '<(skia_include_path)/effects/SkTileImageFilter.h',
     '<(skia_include_path)/effects/SkTransparentShader.h',
     '<(skia_include_path)/effects/SkMagnifierImageFilter.h',
   ],
 }