statistics test: fix the expected "active sockets" values

since the listening socket is now handled by the netmgr, it isn't
counted in the "active sockets" stat anymore, so the expected values
have changed.

bin/tests/system/statistics/tests.sh

@@ -71,7 +71,7 @@ $RNDCCMD -s 10.53.0.3 stats > /dev/null 2>&1
 [ -f ns3/named.stats ] || ret=1
 if [ ! "$CYGWIN" ]; then
     nsock0nstat=`grep "UDP/IPv4 sockets active" ns3/named.stats | awk '{print $1}'`
-    [ 0 -ne ${nsock0nstat:-0} ] || ret=1
+    [ 0 -eq ${nsock0nstat:-0} ] || ret=1
 fi
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=`expr $status + $ret`
@@ -107,7 +107,7 @@ if [ ! "$CYGWIN" ]; then
     ret=0
     echo_i "verifying active sockets output in named.stats ($n)"
     nsock1nstat=`grep "UDP/IPv4 sockets active" ns3/named.stats | awk '{print $1}'`
-    [ `expr $nsock1nstat - $nsock0nstat` -eq 1 ] || ret=1
+    [ `expr ${nsock1nstat:-0} - ${nsock0nstat:-0}` -eq 1 ] || ret=1
     if [ $ret != 0 ]; then echo_i "failed"; fi
     status=`expr $status + $ret`
     n=`expr $n + 1`