Frameworks/base: Wall Werror in libs/storage

Turn on -Wall -Werror in libs/storage.

Change-Id: I314cb32d0a917f9261488f7709d9a78a07b10fea
diff --git a/libs/storage/Android.mk b/libs/storage/Android.mk
index 7a9dd6c..fae2bf7 100644
--- a/libs/storage/Android.mk
+++ b/libs/storage/Android.mk
@@ -9,4 +9,6 @@
 
 LOCAL_MODULE:= libstorage
 
+LOCAL_CFLAGS += -Wall -Werror
+
 include $(BUILD_STATIC_LIBRARY)