Disable AVX2 for Skia in the SyzyAsan build of Chrome.

skia/ext/SkOpts_hsw_stub.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This is SkOpts_hsw.cpp, stubbed out to do nothing. This is used by the
+// SyzyAsan builds because the Syzygy instrumentation pipeline doesn't support
+// the AVX2 and F16C instructions.
+
+namespace SkOpts {
+    void Init_hsw();

[Sébastien Marchand, 2016/12/01 20:48:46]

indentation is weird (to me) and it's weird to have the declaration and the
implementation separated (and no include guard), but it's how this file was
written before its removal in https://codereview.chromium.org/2539453003/

[mtklein_C, 2016/12/01 20:54:18]

These SkOpts::Init_foo() methods are not actually declared in any header, though
they are declared where referenced in SkOpts.cpp.
I think when I wrote this I just wanted to make it clear that this is an extern
function.

This being a .cpp file, I'm not sure why we'd need an include guard or where
we'd put it?

+    void Init_hsw() {}
+}
+