regx/base: fix an integer overflow

use strtol() instead of atoi() in order to handle hostnames
containing a large number.

This is a one-off commit for the release branches since
the regx framework has already been removed from master.

Refs. open-mpi/ompi#6729

Signed-off-by: perrynzhou <perrynzhou@gmail.com>

orte/mca/regx/base/regx_base_default_fns.c

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2016-2018 Intel, Inc.  All rights reserved.
- * Copyright (c) 2018      Research Organization for Information Science
+ * Copyright (c) 2018-2019 Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
  * $COPYRIGHT$
  *
@@ -1056,7 +1056,7 @@ static int regex_parse_node_range(char *base, char *range, int num_digits, char
     for (found = false, i = 0; i < len; ++i) {
         if (isdigit((int) range[i])) {
             if (!found) {
-                start = atoi(range + i);
+                start = strtol(range + i, NULL, 10);
                 found = true;
                 break;
             }