Add optional tags to dalvik.

Change-Id: I29a78ccb6312d12b3ef0ed02cfbc638a5b01db9c
diff --git a/tools/dexdeps/Android.mk b/tools/dexdeps/Android.mk
index 9c2cec7..e1b7e73 100644
--- a/tools/dexdeps/Android.mk
+++ b/tools/dexdeps/Android.mk
@@ -22,6 +22,7 @@
 # ============================================================
 include $(CLEAR_VARS)
 LOCAL_IS_HOST_MODULE := true
+LOCAL_MODULE_TAGS := optional
 LOCAL_MODULE_CLASS := EXECUTABLES
 LOCAL_MODULE := dexdeps