ocaml-ipaddr is marked for autoremoval from testing

[Debian testing autoremoval watch]

ocaml-ipaddr 2.7.0-2 is marked for autoremoval from testing on 2017-11-15

It (build-)depends on packages with these RC bugs:
876725: ppx-deriving: ppx-deriving FTBFS with OCaml 4.05.0
877496: sexplib310: sexplib310 FTBFS: Error: This expression has type Obj.t but 
an expression was expected of type extension_constructor
877507: ppx-core: ppx-core FTBFS: E: Cannot find external tool 'ocamlbuild'