Move CPU features into its own static library.

src/trusted/cpu_features/cpu_features.h

Index: src/trusted/cpu_features/cpu_features.h
diff --git a/src/trusted/cpu_features/cpu_features.h b/src/trusted/cpu_features/cpu_features.h
new file mode 100644
index 0000000000000000000000000000000000000000..88b26e63ce3a93b5a5cf4fd9e43a59628de591db
--- /dev/null
+++ b/src/trusted/cpu_features/cpu_features.h
@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2013 The Native Client Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef NATIVE_CLIENT_SRC_TRUSTED_CPU_FEATURES_CPU_FEATURES_H_
+#define NATIVE_CLIENT_SRC_TRUSTED_CPU_FEATURES_CPU_FEATURES_H_
+
+#include "native_client/src/include/nacl_base.h"
+
+
+EXTERN_C_BEGIN
+
+/*
+ * Forward-declared (but never defined) generic CPU features.
+ * Each architecture needs to cast from this generic type.
+ */
+struct NaClCPUFeaturesAbstract;
+typedef struct NaClCPUFeaturesAbstract NaClCPUFeatures;
+
+EXTERN_C_END
+
+#endif /* NATIVE_CLIENT_SRC_TRUSTED_CPU_FEATURES_CPU_FEATURES_H_ */