Manifest for Android 6.0.0 release 4

default.xml

@@ -3,7 +3,7 @@
 
   <remote  name="aosp"
            fetch=".." />
-  <default revision="refs/tags/android-6.0.0_r2"
+  <default revision="refs/tags/android-6.0.0_r4"
            remote="aosp"
            sync-j="4" />