Use -Werror in frameworks/native/services/inputflinger

* Fix/suppress unused-* warnings.

Bug: 66996870
Test: build with WITH_TIDY=1
Change-Id: If1dd59ea4ee8ce51f7b58ae4581531df301c68a8
diff --git a/services/inputflinger/tests/Android.bp b/services/inputflinger/tests/Android.bp
index 29d93f0..a49c8c8 100644
--- a/services/inputflinger/tests/Android.bp
+++ b/services/inputflinger/tests/Android.bp
@@ -7,7 +7,11 @@
         "InputDispatcher_test.cpp",
     ],
     test_per_src: true,
-    cflags: ["-Wno-unused-parameter"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wno-unused-parameter",
+    ],
     shared_libs = [
         "libcutils",
         "liblog",