Move AsynchronousCloseMonitor here from libcore

AsynchronousCloseMonitor is needed by both
libopenjdk and libjavacore.

Bug: 26127752

(cherry picked from commit 20d3848be7394fb9a4735b8b2148f994ff735d96)

Change-Id: I7d1d89d344180bb1e6bed2e0c83e4e7633122fe0
3 files changed