Fix a NULL pointer dereference which cannot currently happen.

git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@2004 d4fa192b-c00b-0410-8231-f00ffab90ce4

bin/varnishd/hash_classic.c

@@ -167,7 +167,7 @@ hcl_lookup(struct sess *sp, struct objhead *noh)
 			 */
 			if (he2 != NULL)
 				free(he2);
-			if (noh->hash != NULL) {
+			if (noh != NULL && noh->hash != NULL) {
 				free(noh->hash);
 				noh->hash = NULL;
 			}