Use -Werror in hardware/interfaces

* Fix warning of unused result.

Bug: 66996870
Test: build with WITH_TIDY=1
Change-Id: I68e35ddcdeec4290b075ececf14f82335b43e22e
diff --git a/vibrator/1.0/default/Android.bp b/vibrator/1.0/default/Android.bp
index 9170b39..0c7d155 100644
--- a/vibrator/1.0/default/Android.bp
+++ b/vibrator/1.0/default/Android.bp
@@ -31,6 +31,7 @@
 
 cc_binary {
     name: "android.hardware.vibrator@1.0-service",
+    defaults: ["hidl_defaults"],
     init_rc: ["android.hardware.vibrator@1.0-service.rc"],
     vendor: true,
     relative_install_path: "hw",