vim: Inlcude xxd makefile

Change-Id: Id0afa90a193b2a1d827364ee52d224630fea0fe1
diff --git a/Android.mk b/Android.mk
index dbbaacf..4bb58e0 100644
--- a/Android.mk
+++ b/Android.mk
@@ -208,5 +208,4 @@
 
 endif
 
-include $(call all-makefiles-under,$(vim_src))
-
+include $(vim_src)/src/xxd/Android.mk