Use -Werror in frameworks/native/libs/vr

* Suppress/fix warnings of unused variable, parameter,
  private-field, and function.
* Fix warnings about typedef missing declarator.
* Use -Wno-error to keep existing warnings, to fix later.

Bug: 66996870
Test: build with WITH_TIDY=1
Change-Id: Iae96af3f6a17623befe73a9db2c81275fee44fa6
diff --git a/libs/vr/libdvrcommon/Android.bp b/libs/vr/libdvrcommon/Android.bp
index 62aeb79..c7d808b 100644
--- a/libs/vr/libdvrcommon/Android.bp
+++ b/libs/vr/libdvrcommon/Android.bp
@@ -40,6 +40,8 @@
     cflags: [
         "-DLOG_TAG=\"libdvrcommon\"",
         "-DTRACE=0",
+        "-Wall",
+        "-Werror",
     ],
     export_include_dirs: localIncludeFiles,
 
@@ -59,6 +61,11 @@
     tags: ["optional"],
 
     srcs: testFiles,
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wno-unused-parameter",
+    ],
 
     shared_libs: sharedLibraries,