Use -Werror in art/libart_fake

Bug: 66996870
Test: build with WITH_TIDY=1
Change-Id: Ic04b16f2441a7694e39ebb9aafe04b2f70053cf5
diff --git a/libart_fake/Android.mk b/libart_fake/Android.mk
index ed868a5..96e6a14 100644
--- a/libart_fake/Android.mk
+++ b/libart_fake/Android.mk
@@ -22,6 +22,7 @@
 LOCAL_SDK_VERSION := 9
 LOCAL_CPP_EXTENSION := .cc
 LOCAL_SRC_FILES := fake.cc
+LOCAL_CFLAGS := -Wall -Werror
 LOCAL_SHARED_LIBRARIES := liblog
 
 ifdef TARGET_2ND_ARCH