eigrpd: Prevent uninitialized value from being used

eigrpd: Prevent uninitialized value from being used

valgrind is finding:

2141982-==2141982== Conditional jump or move depends on uninitialised value(s)
2141982:==2141982==    at 0x11A7A6: eigrp_metrics_is_same (eigrp_metric.c:134)
2141982-==2141982==    by 0x120360: eigrp_topology_update_distance (eigrp_topology.c:374)
2141982-==2141982==    by 0x124F01: eigrp_get_fsm_event (eigrp_fsm.c:284)
2141982-==2141982==    by 0x12519E: eigrp_fsm_event (eigrp_fsm.c:419)
2141982-==2141982==    by 0x1206A1: eigrp_topology_neighbor_down (eigrp_topology.c:518)
2141982-==2141982==    by 0x11AB3A: eigrp_nbr_delete (eigrp_neighbor.c:178)
2141982-==2141982==    by 0x124494: eigrp_finish_final (eigrpd.c:271)
2141982-==2141982==    by 0x1245A8: eigrp_finish (eigrpd.c:247)
2141982-==2141982==    by 0x124630: eigrp_terminate (eigrpd.c:240)
2141982-==2141982==    by 0x11344B: sigint (eigrp_main.c:112)
2141982-==2141982==    by 0x48F5F32: quagga_sigevent_process (sigevent.c:130)

Prevent this from happening.

Signed-off-by: Donald Sharp <sharpd@nvidia.com>