Move AsynchronousCloseMonitor to its own library.

This change introduces a new shared library, libandroidio,
which encapsulates native IO related APIs that we want to expose,
currently only intra-core but longer term they may be useful
to the framework (e.g. LocalSocket and friends).

Bug: 122881655
Bug: 123744297
Test: m && flashall
Test: atest CtsLibcoreOkHttpTestCases
Test: atest CtsLibcoreTestCases

Change-Id: I4c903d86a41d9ad0337b8e9d17ff0ed129c52413
3 files changed