zclient: Redundant initialization of zclient.zclient_broken to NULL (struct zclient is XCALLOC'ed).
zclient: Rewrite if_connected_reset() as list_delete_all_node().
zclient: Do not remove connected addresses automatically on loss of zebra connection.
pim: Remove connected addresses on loss of zebra connection.
lib: Remove unused if_connected_reset().