Lay groundwork for SkOpts.

This doesn't really do anything yet.  It's just the CPU detection code, skeleton new .cpp files, and a few little .gyp tweaks.

BUG=skia:4117

Committed: https://skia.googlesource.com/skia/+/ce2c5055cee5d5d3c9fc84c1b3eeed4b4d84a827

Review URL: https://codereview.chromium.org/1255193002
diff --git a/src/opts/SkOpts_ssse3.cpp b/src/opts/SkOpts_ssse3.cpp
new file mode 100644
index 0000000..de32966
--- /dev/null
+++ b/src/opts/SkOpts_ssse3.cpp
@@ -0,0 +1,14 @@
+/*
+ * 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"
+
+namespace SkOpts {
+    void Init_ssse3() {
+
+    }
+}