Add function for generating validation signatures.

src/trusted/validator_arm/cpuid_arm.h

Index: src/trusted/validator_arm/cpuid_arm.h
diff --git a/src/trusted/validator_arm/cpuid_arm.h b/src/trusted/validator_arm/cpuid_arm.h
index 47360b3aeb5c1deba00ab557c0d4290e2a11e0f8..dcb4c6c58ac91bb24e3870a32e607db557889896 100644
--- a/src/trusted/validator_arm/cpuid_arm.h
+++ b/src/trusted/validator_arm/cpuid_arm.h
@@ -7,6 +7,9 @@
 #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
@@ -20,11 +23,15 @@ static INLINE void NaClGetCurrentCPUFeatures(NaClCPUFeaturesArm *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 */