* fhandler.cc (fhandler_base::fcntl): Use new O_NONBLOCK_MASK define.

    * fhandler.cc (fhandler_base::fcntl): Use new O_NONBLOCK_MASK define.
        * fhandler.h: Move definitions of O_NOSYMLINK, O_DIROPEN and
        OLD_O_NDELAY from winsup.h to here. Add O_NONBLOCK_MASK define.
        * fhandler_socket.cc (fhandler_socket::close): Add hack to allow
        a graceful shutdown even if shutdown() hasn't been called by the
        application. Add debug output.
        (fhandler_socket::ioctl): Set fhandler's NONBLOCK flag according
        to FIONBIO setting.
        (fhandler_socket::fcntl): Use new O_NONBLOCK_MASK define. Actually
        set `request' before using it.
        * fhandler_tty.cc: Use new O_NONBLOCK_MASK define throughout.
        (fhandler_tty_slave::ioctl): Set fhandler's NONBLOCK flag according
        to FIONBIO setting.
        (fhandler_pty_master::ioctl): Ditto.
        * net.cc (wsock_event::prepare): Compare WSACreateEvent return code
        with `WSA_INVALID_EVENT' according to MSDN.
        * syscalls.cc (_read): Use new O_NONBLOCK_MASK define.