Work around non-blocking fd issue on Windows.
Summary:
I reported the Lwt issue here:
https://github.com/ocsigen/lwt/issues/574. The long story short is that
reading from non-blocking fds on Windows doesn't seem to yield to other
threads, even when the fd isn't ready to read. I'm not sure the cause.
While we could just revert back to using blocking fds, we'd need to
either workaround https://github.com/ocsigen/lwt/issues/569 or ask for
a lwt release and update lwt.
Reviewed By: ljw1004
Differential Revision:
D7603653
fbshipit-source-id:
d6f9b4ed256cfa5b1fb286f9bd41c75748c28ddc