Omit AsynchronousCloseMonitor.cpp in host/macosx and ndk

It's not possible to build  buildAsynchronousCloseMonitor.cpp
for macosx host because of missing __SIGRTMIN. Thankfully,
libcore-host is not built on macosx.

Fixes sdk_phone_armv7-sdk (mac) build

(cherry picked from commit 7b7052ef86e8362857e322e9ce7f73f02f34200f)

Change-Id: Iaba7824c1d2cd3ead59345a0de0e6e0370079b4e
1 file changed