Verify java.lang.ref against upstream OpenJDK 8u121-b13

The Reference and ReferenceQueue classes have basically been completely
reimplemented on Android. So, a top level marker has been added to make
that clear. Reference has also integrated reachabilityFence() from
9+181 so that has its own separate change marker.

The SoftReference only has a documentation change recommending against
using SoftReference for caches.

Bug: 74379469
Test: no functional changes.
Change-Id: I57bf03d848ecf839338b7344c1cb1ce539bd4dd4
3 files changed