Use -Werror in hardware/interfaces

* Remove unused local variables.

Bug: 66996870
Test: build with WITH_TIDY=1
Change-Id: I48dbbf670cc9eeff2391983788983420f8547cc9
diff --git a/wifi/1.0/vts/functional/Android.bp b/wifi/1.0/vts/functional/Android.bp
index e164cdf..10f1987 100644
--- a/wifi/1.0/vts/functional/Android.bp
+++ b/wifi/1.0/vts/functional/Android.bp
@@ -16,6 +16,7 @@
 
 cc_library_static {
     name: "VtsHalWifiV1_0TargetTestUtil",
+    defaults: ["hidl_defaults"],
     srcs: [
 
         "wifi_hidl_call_util_selftest.cpp",