json-c: Ignore clang warnings for unused-parameter

Change-Id: I5d0505caf8108a72ad0371f6799728924454f09f
diff --git a/Android.mk b/Android.mk
index 139a10c..17558e2 100644
--- a/Android.mk
+++ b/Android.mk
@@ -2,6 +2,7 @@
 include $(CLEAR_VARS)
 LOCAL_MODULE := libjson
 LOCAL_PATH := $(LIBJSON_ROOT)
+LOCAL_CFLAGS := -Werror -Wno-error=unused-parameter
 LOCAL_C_INCLUDES += $(TARGET_OUT_INTERMEDIATES)/KERNEL_OBJ/usr/include
 LOCAL_ADDITIONAL_DEPENDENCIES += $(TARGET_OUT_INTERMEDIATES)/KERNEL_OBJ/usr
 LOCAL_COPY_HEADERS_TO := libjson/inc