dump: return a negative value in case of error

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-dump.c

@@ -1394,6 +1394,7 @@ static int dump_one_task(const struct pstree_item *item)
 
 	parasite_ctl = parasite_infect_seized(pid, &vma_area_list);
 	if (!parasite_ctl) {
+		ret = -1;
 		pr_err("Can't infect (pid: %d) with parasite\n", pid);
 		goto err;
 	}