wxx: Fix broken TCP networking (regression)

It is broken since commit c619644067.

Reported-by: Michael Fritscher <michael@fritscher.net>
Tested-by: Michael Fritscher <michael@fritscher.net>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>

slirp/tcp_input.c

@@ -659,6 +659,7 @@ findso:
 	  }
 
 	  if ((tcp_fconnect(so, so->so_ffamily) == -1) &&
+              (errno != EAGAIN) &&
               (errno != EINPROGRESS) && (errno != EWOULDBLOCK)
           ) {
 	    uint8_t code;