Silence unused value compiler warning.

Change-Id: I33ac08f5a6f50b378da036563571497205ce7d94
diff --git a/Makefile b/Makefile
index 7f82db6..e419813 100644
--- a/Makefile
+++ b/Makefile
@@ -45,7 +45,7 @@
 
 CPPFLAGS=$(INCLUDES) -g -O0 -MD -MP
 CXXFLAGS=-Wall -Werror -Wno-unused -Winit-self -Wpointer-arith	-Wunused-parameter \
-	-Werror=sign-compare -ftest-coverage -fno-permissive \
+	-Werror=sign-compare -ftest-coverage -fno-permissive -Wunused-value \
 	-Wno-deprecated-declarations -fno-exceptions -DKEYMASTER_NAME_TAGS \
 	$(COMPILER_SPECIFIC_ARGS)
 
diff --git a/android_keymaster_test.cpp b/android_keymaster_test.cpp
index 219146b..f5a17fb 100644
--- a/android_keymaster_test.cpp
+++ b/android_keymaster_test.cpp
@@ -33,7 +33,7 @@
 extern "C" {
 int __android_log_print(int prio, const char* tag, const char* fmt);
 int __android_log_print(int prio, const char* tag, const char* fmt) {
-    prio, tag, fmt;
+    (void)prio, (void)tag, (void)fmt;
     return 0;
 }
 }  // extern "C"