ospfd: restart spf when distance is updated

ospfd: restart spf when distance is updated

if r1 has a route received from a neighbor with the default administrative
distance configured

    r1# sh ip route
    Codes: K - kernel route, C - connected, S - static, R - RIP,
           O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
           T - Table, v - VNC, V - VNC-Direct, A - Babel, F - PBR,
           f - OpenFabric,
           > - selected route, * - FIB route, q - queued, r - rejected, b - backup
           t - trapped, o - offload failure

    O>* 1.1.1.1/32 [110/20] via 10.0.12.2, r1-r2-eth0, weight 1, 00:00:41

if we change the administrative distance

    r1(config)# router ospf
    r1(config-router)# distance 50

this is not applied as there are no changes in the routing table

    r1# sh ip route
    Codes: K - kernel route, C - connected, S - static, R - RIP,
           O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
           T - Table, v - VNC, V - VNC-Direct, A - Babel, F - PBR,
           f - OpenFabric,
           > - selected route, * - FIB route, q - queued, r - rejected, b - backup
           t - trapped, o - offload failure

    O>* 1.1.1.1/32 [110/20] via 10.0.12.2, r1-r2-eth0, weight 1, 00:00:13

This commit will force the update of the routing table with the new configured distance

    r1# sh ip route
    Codes: K - kernel route, C - connected, S - static, R - RIP,
           O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
           T - Table, v - VNC, V - VNC-Direct, A - Babel, F - PBR,
           f - OpenFabric,
           > - selected route, * - FIB route, q - queued, r - rejected, b - backup
           t - trapped, o - offload failure

    O>* 1.1.1.1/32 [50/20] via 10.0.12.2, r1-r2-eth0, weight 1, 00:00:14

Signed-off-by: ckishimo <carles.kishimoto@gmail.com>