Use -Werror in hardware/interfaces

* Remove unused local variables.

Bug: 66996870
Test: build with WITH_TIDY=1
Change-Id: I48dbbf670cc9eeff2391983788983420f8547cc9
diff --git a/radio/1.0/vts/functional/Android.bp b/radio/1.0/vts/functional/Android.bp
index 82a8a72..61136ae 100644
--- a/radio/1.0/vts/functional/Android.bp
+++ b/radio/1.0/vts/functional/Android.bp
@@ -50,6 +50,7 @@
 
 cc_library_static {
     name: "RadioVtsTestUtilBase",
+    defaults: ["hidl_defaults"],
     srcs : [
         "vts_test_util.cpp"
     ],