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
diff --git a/libandroidio.map.txt b/libandroidio.map.txt
new file mode 100644
index 0000000..cb6e879
--- /dev/null
+++ b/libandroidio.map.txt
@@ -0,0 +1,11 @@
+LIBANDROIDIO_1 {
+  global:
+    async_close_monitor_create;
+    async_close_monitor_destroy;
+    async_close_monitor_signal_blocked_threads;
+    async_close_monitor_static_init;
+    async_close_monitor_was_signalled;
+
+  local:
+    *;
+};