slirp: Fix typo in net_slirp_hostfwd_remove

Report an error when err is nonzero, not when it is zero.
Signed-off-by: NGeoffrey Thomas <geofft@ldpreload.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

net/slirp.c

@@ -351,7 +351,7 @@ void net_slirp_hostfwd_remove(Monitor *mon, const QDict *qdict)
                                host_addr, host_port);
 
     monitor_printf(mon, "host forwarding rule for %s %s\n", src_str,
-                   err ? "removed" : "not found");
+                   err ? "not found" : "removed");
     return;
 
  fail_syntax: