Suppress unused-parameter warnings and enable -Werror libwnndict target.

Test: make libwnndict no longer produces warnings.
Change-Id: Iea1f6cf4ad8d147f60c56dddd85eceece5d62da7
diff --git a/libs/libwnnDictionary/Android.mk b/libs/libwnnDictionary/Android.mk
index b7b88b2..456b148 100644
--- a/libs/libwnnDictionary/Android.mk
+++ b/libs/libwnnDictionary/Android.mk
@@ -28,6 +28,6 @@
 	$(LOCAL_PATH)/include $(LOCAL_PATH)
 
 LOCAL_CFLAGS += \
-	 -O
+	 -O -Wno-unused-parameter -Werror
 
 include $(BUILD_SHARED_LIBRARY)