Stop segfaulting when trying to set a nonexistant waiter

We failed to properly check for the end of the list of waiters.
Handle this correctly and add a test case

Fixes #428


git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@3825 d4fa192b-c00b-0410-8231-f00ffab90ce4

bin/varnishd/cache_acceptor.c

@@ -368,7 +368,7 @@ VCA_tweak_waiter(struct cli *cli, const char *arg)
 		vca_act = NULL;
 		return;
 	}
-	for (i = 0; vca_waiters[i]->name; i++) {
+	for (i = 0; vca_waiters[i]; i++) {
 		if (!strcmp(arg, vca_waiters[i]->name)) {
 			vca_act = vca_waiters[i];
 			return;

bin/varnishtest/tests/b00008.vtc

@@ -19,3 +19,7 @@ varnish v1 -start
 varnish v1 -cliok "help"
 
 varnish v1 -cliok "stats"
+
+varnish v1 -cliok "param.set waiter default"
+
+varnish v1 -clierr 106 "param.set waiter HASH(0x8839c4c)"