Use -Werror in hardware/interfaces

* Remove unused local variables.

Bug: 66996870
Test: build with WITH_TIDY=1
Change-Id: I48dbbf670cc9eeff2391983788983420f8547cc9
diff --git a/drm/1.0/vts/functional/Android.bp b/drm/1.0/vts/functional/Android.bp
index b45ce84..18aebee 100644
--- a/drm/1.0/vts/functional/Android.bp
+++ b/drm/1.0/vts/functional/Android.bp
@@ -16,6 +16,7 @@
 
 cc_test {
     name: "VtsHalDrmV1_0TargetTest",
+    defaults: ["VtsHalTargetTestDefaults"],
     srcs: [
         "drm_hal_clearkey_test.cpp",
         "drm_hal_vendor_test.cpp",