No longer need mpls_ifmgr_get_address mpls_ifmgr_open_if and
mpls_ifmgr_close_if. we now need mpls_ifmgr_get_name
ldp_if nolonger needs localaddress and name
If an ldp_addr or ldp_nexthop are added which have a if_handle
for an interface which doesn't exist yet, leave the iff pointer NULL.
When the interface is added it will search for 'dangling' ldp_addr
and ldp_nexthop and attach them. These are also correctly detached
when the interface is deleted.
[git-p4: depot-paths = "//depot/ldp-portable/": change = 405]