Add function for generating validation signatures.

src/trusted/validator_arm/cpuid_arm.h

 /*
  * Copyright (c) 2012 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_VALIDATOR_ARM_CPUID_ARM_H
 #define NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_ARM_CPUID_ARM_H
 
+#include "native_client/src/include/portability.h"
+
+EXTERN_C_BEGIN
 
 typedef struct {
   /* Add a dummy field because a zero-sized structure causes skew between C and
    * C++.
    */
   int bogus;
 } NaClCPUFeaturesArm;
 
 static INLINE void NaClGetCurrentCPUFeatures(NaClCPUFeaturesArm *cpu_features) {
   UNREFERENCED_PARAMETER(cpu_features);
 }
 
 static INLINE void NaClSetAllCPUFeatures(NaClCPUFeaturesArm *cpu_features) {
-  UNREFERENCED_PARAMETER(cpu_features);
+  /* Needed for testing. */
+  cpu_features->bogus = 1;
 }
 
 static INLINE void NaClClearCPUFeatures(NaClCPUFeaturesArm *cpu_features) {
-  UNREFERENCED_PARAMETER(cpu_features);
+  /* Needed for testing. */
+  cpu_features->bogus = 0;
 }
 
+EXTERN_C_END
+
 #endif /* NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_ARM_CPUID_ARM_H */