Use built in delay function

git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@3245 d4fa192b-c00b-0410-8231-f00ffab90ce4

bin/varnishtest/tests/v00014.vtc

@@ -38,7 +38,7 @@ client c1 {
 	expect resp.status == 500
 } -run
 
-shell "sleep 1"
+delay 1
 
 client c2 {
 	txreq