Reorganize to keep similar code together.

src/opts/SkOpts_sse41.cpp

 /*
  * 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 "SkOpts.h"
+
 #define SK_OPTS_NS sse41
 #include "SkBlurImageFilter_opts.h"
 
 namespace SkOpts {
     void Init_sse41() {
         static const auto x = sse41::kX, y = sse41::kY;
         box_blur_xx = sse41::box_blur<x,x>;
         box_blur_xy = sse41::box_blur<x,y>;
         box_blur_yx = sse41::box_blur<y,x>;
     }
 }