Add capability for SkColorXform to output half floats

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"
 #include "SkBlitRow_opts.h"
 #include "SkBlend_opts.h"
 #include "SkColorXform_opts.h"
 
 namespace SkOpts {
     void Init_sse41() {
         box_blur_xx          = sse41::box_blur_xx;
         box_blur_xy          = sse41::box_blur_xy;
         box_blur_yx          = sse41::box_blur_yx;
         srcover_srgb_srgb    = sse41::srcover_srgb_srgb;
         blit_row_s32a_opaque = sse41::blit_row_s32a_opaque;
 
         color_xform_RGB1_to_2dot2  = sse41::color_xform_RGB1_to_2dot2;
         color_xform_RGB1_to_srgb   = sse41::color_xform_RGB1_to_srgb;
         color_xform_RGB1_to_table  = sse41::color_xform_RGB1_to_table;
+        color_xform_RGB1_to_linear = sse41::color_xform_RGB1_to_linear;
     }
 }