Clean up SSSE3 and SSE4 stubs.

src/opts/SkBlitRow_opts_SSE4.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 "SkBlitRow_opts_SSE4.h"
-
-// Some compilers can't compile SSSE3 or SSE4 intrinsics.  We give them stub methods.
-// The stubs should never be called, so we make them crash just to confirm that.
-#if SK_CPU_SSE_LEVEL < SK_CPU_SSE_LEVEL_SSE41
-void S32A_Opaque_BlitRow32_SSE4(SkPMColor* SK_RESTRICT, const SkPMColor* SK_RESTRICT, int, U8CPU) {
-    sk_throw();
-}
-
-#else
-
-#include <smmintrin.h>      // SSE4.1 intrinsics
 #include "SkColorPriv.h"
 #include "SkColor_opts_SSE2.h"
 #include "SkMSAN.h"
 
 void S32A_Opaque_BlitRow32_SSE4(SkPMColor* SK_RESTRICT dst,
                                 const SkPMColor* SK_RESTRICT src,
                                 int count,
                                 U8CPU alpha) {
     sk_msan_assert_initialized(src, src+count);
 
@@ skipping 33 matching lines @@
     }
 
     // Wrap up the last <= 15 pixels.
     for (int i = count16*16; i < count; i++) {
         // This check is not really necessarily, but it prevents pointless autovectorization.
         if (src[i] & 0xFF000000) {
             dst[i] = SkPMSrcOver(src[i], dst[i]);
         }
     }
 }
-
-#endif