xmlrpcpp: Treat all warnings as errors

BUG: 28475384
Change-Id: Ied3df3c48a2ed153ec8090ff0fdc8d774d9e4903
diff --git a/Android.mk b/Android.mk
index cb5a73e..a88f2ab 100644
--- a/Android.mk
+++ b/Android.mk
@@ -6,7 +6,7 @@
 
 LOCAL_CLANG := true
 LOCAL_RTTI_FLAG := -frtti
-LOCAL_CPPFLAGS := -Wall -fexceptions
+LOCAL_CPPFLAGS := -Wall -Werror -fexceptions
 LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/src
 
 LOCAL_SRC_FILES := $(call all-cpp-files-under,src)