From: Stewart Forster <slf@connect.com.au>

From:    Stewart Forster <slf@connect.com.au>
        This is the final patch that I decided upon that avoids extra system
calls (ie. faster).

        It adds two extra flags, FD_NOLINGER, and FD_NONBLOCKING to allow
for easy testing of these conditions when deciding what to do in comm_close().
It also allows for easy changing of the doaioclose test in the future when
it's decided what actually takes precedence.