Refactor SkBlurImageFilter_Opts.h.

Refactor box_blur() into a single driver function which
SSE*, NEON and generic code paths can use. I've used macros
to do this in order to keep debug performance reasonable,
but it's fairly ugly. I'm open to other suggestions.

BUG=skia:
CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot

Review URL: https://codereview.chromium.org/1408003007
1 file changed