config: fix ns leak in parse_join_ns

coverity CID 389192:

550static int parse_join_ns(const char *ptr)
551{
...
553        char *ns;
554
   1. alloc_fn: Storage is returned from allocation function strdup.
   2. var_assign: Assigning: ___p = storage returned from strdup(ptr).
   3. Condition !___p, taking false branch.
   4. leaked_storage: Variable ___p going out of scope leaks the storage it points to.
   5. var_assign: Assigning: ns = ({...; ___p;}).
555        ns = xstrdup(ptr);
   6. Condition ns == NULL, taking false branch.
556        if (ns == NULL)
557                return -1;
558
   7. noescape: Resource ns is not freed or pointed-to in strchr.
559        aux = strchr(ns, ':');
   8. Condition aux == NULL, taking true branch.
560        if (aux == NULL)
   CID 389192 (#1 of 1): Resource leak (RESOURCE_LEAK)9. leaked_storage: Variable ns going out of scope leaks the storage it points to.
561                return -1;

We should free ns string after we finish it's use in parse_join_ns,
easiest way to do it is to use cleanup_free attribute.

Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>

criu/config.c

@@ -549,7 +549,7 @@ static size_t parse_size(char *optarg)
 static int parse_join_ns(const char *ptr)
 {
 	char *aux, *ns_file, *extra_opts = NULL;
-	char *ns;
+	cleanup_free char *ns = NULL;
 
 	ns = xstrdup(ptr);
 	if (ns == NULL)