Use -Werror in frameworks/native/cmds

* Remove or comment out unused variables/functions.

Bug: 66996870
Test: build with WITH_TIDY=1
Change-Id: I15a463eb9a20bc12787c104f671063ceeafaa1cc
diff --git a/cmds/atrace/Android.bp b/cmds/atrace/Android.bp
index 5548699..e06f937 100644
--- a/cmds/atrace/Android.bp
+++ b/cmds/atrace/Android.bp
@@ -3,6 +3,10 @@
 cc_binary {
     name: "atrace",
     srcs: ["atrace.cpp"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
 
     shared_libs: [
         "libbinder",