Don't install afar and dexpreopt-wrapper on system while building tests.
diff --git a/tools/dexpreopt/dexopt-wrapper/Android.mk b/tools/dexpreopt/dexopt-wrapper/Android.mk
index e6ca389..ae2b6a3 100644
--- a/tools/dexpreopt/dexopt-wrapper/Android.mk
+++ b/tools/dexpreopt/dexopt-wrapper/Android.mk
@@ -31,6 +31,6 @@
 
 LOCAL_MODULE := dexopt-wrapper
 
-LOCAL_MODULE_TAGS := tests
+LOCAL_MODULE_TAGS := optional
 
 include $(BUILD_EXECUTABLE)