ART: (Partially) fix lock aliasing

On monitor-exit, we must unlock all the registers which purport to
be locked at the current lock depth. These are lock aliases.

Bug: 20102779
Bug: 21169615
Bug: 21988678
Bug: 23300986
Change-Id: I6604871fc778d8f0ca9a99f6aad16a99ab62c599