Update syntax for ndnpeek/ndnping in integration tests

refs #3694

Change-Id: I82ed673f5cf48da942dcfe59b36e76548bcb07bc
diff --git a/test_linkfail/ping.sh b/test_linkfail/ping.sh
index 17a7af3..6d4779c 100755
--- a/test_linkfail/ping.sh
+++ b/test_linkfail/ping.sh
@@ -7,7 +7,7 @@
 
 ndnping -c 25 /B &> logs/${LOGPREFIX}_ping_A.log
 
-LOSS=$(sed -n 's/.*received, \([^,]*\) packet loss.*/\1/p' logs/${LOGPREFIX}_ping_A.log)
+LOSS=$(sed -n 's/.*nacked, \([^,]*\) packet loss.*/\1/p' logs/${LOGPREFIX}_ping_A.log)
 MAXRTT=$(sed -n 's/rtt.* = .*\/\([^)]*\).*\/.*/\1/p' logs/${LOGPREFIX}_ping_A.log)
 
 [[ $LOSS == '0%' ]] && [[ $(echo $MAXRTT | sed 's/\..*//') -le 100 ]]