Add stub for avx.

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2087343002
CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot

Review-Url: https://codereview.chromium.org/2087343002

gyp/opts.gypi

@@ -49,13 +49,13 @@
         'sse41_sources': [
             '<(skia_src_path)/opts/SkOpts_sse41.cpp',
         ],
+        'avx_sources': [
+            '<(skia_src_path)/opts/SkOpts_avx.cpp',
+        ],
         # These targets are empty, but XCode doesn't like that, so add an empty file to each.
         'sse42_sources': [
             '<(skia_src_path)/core/SkForceCPlusPlusLinking.cpp',
         ],
-        'avx_sources': [
-            '<(skia_src_path)/core/SkForceCPlusPlusLinking.cpp',
-        ],
         'avx2_sources': [
             '<(skia_src_path)/core/SkForceCPlusPlusLinking.cpp',
         ],

src/core/SkOpts.cpp

@@ -90,7 +90,7 @@ namespace SkOpts {
     void Init_ssse3();
     void Init_sse41();
     void Init_sse42() {}
-    void Init_avx() {}
+    void Init_avx();
     void Init_avx2() {}
 
     static void init() {

src/opts/SkBlend_opts.h

@@ -15,6 +15,10 @@ ninja -C out/Release dm nanobench ; and ./out/Release/dm --match Blend_opts ; an
 #include "SkNx.h"
 #include "SkPM4fPriv.h"
 
+#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
+    #include <immintrin.h>
+#endif
+
 namespace SK_OPTS_NS {
 
 // An implementation of SrcOver from bytes to bytes in linear space that takes advantage of the

src/opts/SkOpts_avx.cpp

@@ -0,0 +1,15 @@
+/*
+ * Copyright 2016 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 sk_avx
+#include "SkBlend_opts.h"
+
+namespace SkOpts {
+    void Init_avx() { }
+}