Merge pull request #15082 from louis-6wind/fix-iff-lower-up

lib: take into account the Linux IFF_LOWER_UP flag

diff --cc lib/if.c
Simple merge

diff --cc tests/topotests/ospf_basic_functionality/test_ospf_single_area.py
Simple merge

diff --cc zebra/fpm_listener.c
index 63977633a93b87ceec59547f8a0f90aa71898c75,65067d2ddacce62fef1ab8dd76a089ad1d89359d..7d84c706d40849710efca1b076d94ee7af0e44b9
--- 1/zebra/fpm_listener.c
--- 2/zebra/fpm_listener.c
+++ b/zebra/fpm_listener.c
@@@ -417,10 -405,9 +417,10 @@@ static int netlink_msg_ctx_add_nh(struc
  static int parse_multipath_attr(struct netlink_msg_ctx *ctx,
                                struct rtattr *mpath_rtattr)
  {
-       size_t len;
+       int len;
        struct rtnexthop *rtnh;
        struct rtattr *rtattrs[RTA_MAX + 1];
 +      struct rtattr *tb[RTA_MAX + 1];
        struct rtattr *gateway;
        const char *err_msg;