pru_abort() by closing a listen socket while completed connections are
presenting in its listen queue. Unfortunately, it's difficult to
trigger the other two pru_abort() cases using user APIs, so they are
not covered by this test.
mode. Support both connection via connect() and sendto(), but don't
compile in sendto() for now, since netipx doesn't appear to actually
implement that (doh).
times, with variable length sleeps between socket() and close(). This
will help to ensure that IPX/SPX timers fire while the sockets are
open, and hence have PCB's on the IPX pcb list, so that if timers are
going to stumble over PCB types they don't expect, it will happen as
part of this test.
