Use VSB_destroy() where applicable.

bin/varnishtest/vtc_barrier.c

@@ -306,7 +306,7 @@ barrier_sock_sync(struct barrier *b, struct vtclog *vl)
 		vtc_fatal(vl, "Barrier(%s) connection failed: %s",
 		    b->name, err);
 
-	VSB_delete(vsb);
+	VSB_destroy(&vsb);
 
 	/* emulate pthread_cond_wait's behavior */
 	AZ(pthread_mutex_unlock(&b->mtx));

bin/varnishtest/vtc_client.c

@@ -225,7 +225,7 @@ client_thread(void *priv)
 	vsb = macro_expand(vl, c->connect);
 	AN(vsb);
 #if !defined(__sun)
-	pthread_cleanup_push((void (*)(void *))VSB_delete, vsb);
+	pthread_cleanup_push((void (*)(void *))VSB_destroy, &vsb);
 #endif
 	c->addr = VSB_data(vsb);
 
@@ -252,7 +252,7 @@ client_thread(void *priv)
 	pthread_cleanup_pop(0);
 #endif
 	pthread_cleanup_pop(0);
-	VSB_delete(vsb);
+	VSB_destroy(&vsb);
 	vtc_logclose(vl);
 	return (NULL);
 }

bin/varnishtest/vtc_proxy.c

@@ -129,6 +129,6 @@ vtc_send_proxy(int fd, int version, const struct suckaddr *sac,
 
 	AZ(VSB_finish(vsb));
 	i = VSB_tofile(vsb, fd);
-	VSB_delete(vsb);
+	VSB_destroy(&vsb);
 	return (i);
 }