Add capability for SkColorXform to output half floats

src/opts/SkOpts_sse41.cpp

Index: src/opts/SkOpts_sse41.cpp
diff --git a/src/opts/SkOpts_sse41.cpp b/src/opts/SkOpts_sse41.cpp
index 56ac386333a692a51af570daeb405c6609c23176..e1e024d9483c0edc876599429fc39397171a276e 100644
--- a/src/opts/SkOpts_sse41.cpp
+++ b/src/opts/SkOpts_sse41.cpp
@@ -24,5 +24,6 @@ namespace SkOpts {
         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;
     }
 }