ocamlbuild plugin - support rpath and "-static" when linking

link.rpath

/path/to/library1
/path/to/library2

myocamlbuild.ml

open Ocamlbuild_plugin

let rpaths = string_list_of_file "link.rpath"
let static_flags = S [A "-cclib"; A "-static"]

let () = dispatch begin function
    | After_rules ->
      List.iter (
        fun path ->
          let rpath_flags = S [A "-cclib"; A ("-Wl,-rpath," ^ path)] in
          flag ["ocaml"; "link"; "program"; "rpath"] rpath_flags;
          flag ["ocaml"; "link"; "library"; "rpath"] rpath_flags;
      ) rpaths;
      flag ["ocaml"; "link"; "program"; "static"] static_flags;
    | _ -> ()
  end