Turn on extra compiler checks

Turn on the compiler flags -Wall -Wextra -Werror to make sure no
compiler warnings are added to the project.

Eliminate all unused arguments. Remove unused variables in code.

Change-Id: I0940ba897ac716b4a256f94fcd671f1ff5abc62c
diff --git a/keystore/Android.mk b/keystore/Android.mk
index 9faf5c2..d4fbe06 100644
--- a/keystore/Android.mk
+++ b/keystore/Android.mk
@@ -17,6 +17,7 @@
 LOCAL_PATH := $(call my-dir)
 
 include $(CLEAR_VARS)
+LOCAL_CFLAGS := -Wall -Wextra -Werror
 LOCAL_SRC_FILES := keystore.cpp keyblob_utils.cpp
 LOCAL_C_INCLUDES := external/openssl/include
 LOCAL_SHARED_LIBRARIES := libcutils libcrypto libhardware
@@ -25,6 +26,7 @@
 include $(BUILD_EXECUTABLE)
 
 include $(CLEAR_VARS)
+LOCAL_CFLAGS := -Wall -Wextra -Werror
 LOCAL_SRC_FILES := keystore_cli.cpp
 LOCAL_C_INCLUDES := external/openssl/include
 LOCAL_SHARED_LIBRARIES := libcutils libcrypto
@@ -34,6 +36,7 @@
 
 # Library for keystore clients
 include $(CLEAR_VARS)
+LOCAL_CFLAGS := -Wall -Wextra -Werror
 LOCAL_SRC_FILES := keystore_client.cpp keyblob_utils.cpp
 LOCAL_SHARED_LIBRARIES := libcutils
 LOCAL_MODULE := libkeystore_client