pbrd: fix disorder of rule

[anlancs]

When pbr_nht_delete_individual_nexthop() removes nexthop, the pbr common is indeed updated when the last one is being updated or deleted as comment said in this function. But if there are more than one nexthops in one pbr-map instance, it wrongly doesn't remove the ip rule which is previously sent to the kernel. In this case, it will lead to the disorder of rule in kernel.

With this configuration: ( The nexthops of "1300::3" and "3.3.3.3" is in "vrf1", and not in vrf "default".)

pbr-map aa seq 1
 match dst-ip 9.9.9.9/32
 set nexthop 3.3.3.3 nexthop-vrf vrf1
exit
!
pbr-map aa seq 2
 match dst-ip 9999::9/32
 set nexthop 1300::3 nexthop-vrf vrf1
exit
!

int vlan100
  pbr-policy  aa
exit

Now all is okay.

Then, trigger pbr_nht_delete_individual_nexthop() by:

anlan# config
anlan(config)# pbr-map aa seq 1
anlan(config-pbr-map)# set nexthop 3.3.3.3
anlan(config-pbr-map)# 

Now ip rule/ip route will be in disorder/inconsistent status. For example, ip rule is with table 10001, but there is empty things in ip table 10001.