GYP groudwork for half-float opts support.

gyp/opts.gypi

 {
         'none_sources': [
             '<(skia_src_path)/opts/SkBitmapProcState_opts_none.cpp',
             '<(skia_src_path)/opts/SkBlitMask_opts_none.cpp',
             '<(skia_src_path)/opts/SkBlitRow_opts_none.cpp',
             '<(skia_src_path)/opts/SkBlurImage_opts_none.cpp',
             '<(skia_src_path)/opts/SkMorphology_opts_none.cpp',
             '<(skia_src_path)/opts/SkTextureCompression_opts_none.cpp',
             '<(skia_src_path)/opts/SkUtils_opts_none.cpp',
             '<(skia_src_path)/opts/SkXfermode_opts_none.cpp',
@@ skipping 15 matching lines @@
             '<(skia_src_path)/opts/SkBitmapProcState_matrixProcs_neon.cpp',
             '<(skia_src_path)/opts/SkBlitMask_opts_arm_neon.cpp',
             '<(skia_src_path)/opts/SkBlitRow_opts_arm_neon.cpp',
             '<(skia_src_path)/opts/SkBlurImage_opts_neon.cpp',
             '<(skia_src_path)/opts/SkMorphology_opts_neon.cpp',
             '<(skia_src_path)/opts/SkTextureCompression_opts_neon.cpp',
             '<(skia_src_path)/opts/SkXfermode_opts_arm_neon.cpp',
             '<(skia_src_path)/opts/memset16_neon.S',
             '<(skia_src_path)/opts/memset32_neon.S',
         ],
+        'neon_fp16_sources': [
+        ],
         'arm64_sources': [
             '<(skia_src_path)/opts/SkBitmapProcState_arm_neon.cpp',
             '<(skia_src_path)/opts/SkBitmapProcState_matrixProcs_neon.cpp',
             '<(skia_src_path)/opts/SkBitmapProcState_opts_arm.cpp',
             '<(skia_src_path)/opts/SkBlitMask_opts_arm.cpp',
             '<(skia_src_path)/opts/SkBlitMask_opts_arm_neon.cpp',
             '<(skia_src_path)/opts/SkBlitRow_opts_arm.cpp',
             '<(skia_src_path)/opts/SkBlitRow_opts_arm_neon.cpp',
             '<(skia_src_path)/opts/SkBlurImage_opts_arm.cpp',
             '<(skia_src_path)/opts/SkBlurImage_opts_neon.cpp',
@@ skipping 28 matching lines @@
             '<(skia_src_path)/opts/SkXfermode_opts_SSE2.cpp',
             '<(skia_src_path)/opts/opts_check_x86.cpp',
         ],
         'ssse3_sources': [
             '<(skia_src_path)/opts/SkBitmapProcState_opts_SSSE3.cpp',
         ],
         'sse41_sources': [
             '<(skia_src_path)/opts/SkBlurImage_opts_SSE4.cpp',
             '<(skia_src_path)/opts/SkBlitRow_opts_SSE4.cpp',
         ],
+        'avx_sources': [
+        ],
 }