ETHER: Fix possible race conditions when closing a network device

Added pcap version to the SCP output of SHOW VERSION command.

slirp_glue/sim_slirp.c

@@ -595,6 +595,8 @@ fd_set rfds, wfds, xfds;
 fd_set save_rfds, save_wfds, save_xfds;
 int nfds;
 
+if (!slirp)                         /* Not active? */
+    return -1;                      /* That's an error */
 /* Populate the GPollFDs from slirp */
 g_array_set_size (slirp->gpollfds, 1);  /* Leave the doorbell chime alone */
 slirp_pollfds_fill(slirp->gpollfds, &slirp_timeout);