AAPT2: Convert Android.mk to Android.bp

Change-Id: I6c563993b57e3f04165ca57743f9a2878aba556c
diff --git a/Android.bp b/Android.bp
index 9088315..81d6dab 100644
--- a/Android.bp
+++ b/Android.bp
@@ -14,6 +14,7 @@
 
 subdirs = [
     "libs/*",
+    "tools/*",
     "native/android",
     "native/graphics/jni",
 ]