Add default -Werror to frameworks/ml/nn.

Bug: 66996870
Test: build with WITH_TIDY=1
Change-Id: I6c7fb32b0abaf9b1dc03292daf7c584b1648eeeb
diff --git a/cc/config/global.go b/cc/config/global.go
index 5d1f7c4..243a2f9 100644
--- a/cc/config/global.go
+++ b/cc/config/global.go
@@ -125,7 +125,6 @@
 		"device/",
 		"frameworks/av/media/libeffects/factory/",
 		"frameworks/av/media/libstagefright/codecs/",
-		"frameworks/ml/nn/",
 		"frameworks/native/libs/vr/libbufferhub/",
 		"vendor/",
 	}