Use -Werror in frameworks/base/tools/streaming_proto

* Remove unused constants.

Bug: 66996870
Test: build with WITH_TIDY=1
Change-Id: I43940e8c446bab25b8fa841ec8c17885ab5d88ed
diff --git a/tools/streaming_proto/Android.bp b/tools/streaming_proto/Android.bp
index dc5c14e..4e9391d 100644
--- a/tools/streaming_proto/Android.bp
+++ b/tools/streaming_proto/Android.bp
@@ -24,6 +24,10 @@
         "stream_proto_utils.cpp",
         "string_utils.cpp",
     ],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
 
     shared_libs: ["libprotoc"],
 }