buildDunePackage: new support function; use it to refactor some OCaml derivations

pkgs/development/ocaml-modules/cstruct/default.nix

@@ -1,8 +1,9 @@
-{ stdenv, fetchurl, ocaml, dune, findlib, sexplib, ocplib-endian }:
+{ stdenv, fetchurl, buildDunePackage, sexplib, ocplib-endian }:
 
-stdenv.mkDerivation rec {
-  name = "ocaml${ocaml.version}-cstruct-${version}";
+buildDunePackage rec {
+  pname = "cstruct";
   version = "3.1.1";
+
   src = fetchurl {
     url = "https://github.com/mirage/ocaml-cstruct/releases/download/v${version}/cstruct-${version}.tbz";
     sha256 = "1x4jxsvd1lrfibnjdjrkfl7hqsc48rljnwbap6faanj9qhwwa6v2";
@@ -10,19 +11,12 @@ stdenv.mkDerivation rec {
 
   unpackCmd = "tar -xjf $curSrc";
 
-  buildInputs = [ ocaml dune findlib ];
-
   propagatedBuildInputs = [ sexplib ocplib-endian ];
 
-  buildPhase = "dune build -p cstruct";
-
-  inherit (dune) installPhase;
-
   meta = {
     description = "Access C-like structures directly from OCaml";
     license = stdenv.lib.licenses.isc;
     homepage = "https://github.com/mirage/ocaml-cstruct";
     maintainers = [ stdenv.lib.maintainers.vbgl ];
-    inherit (ocaml.meta) platforms;
   };
 }