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

pkgs/development/ocaml-modules/io-page/default.nix

@@ -1,23 +1,19 @@
-{ stdenv, fetchzip, ocaml, findlib, dune, configurator, cstruct }:
+{ stdenv, fetchzip, buildDunePackage, configurator, cstruct }:
 
-let version = "2.0.1"; in
-
-stdenv.mkDerivation {
-  name = "ocaml${ocaml.version}-io-page-${version}";
+buildDunePackage rec {
+  pname = "io-page";
+  version = "2.0.1";
 
   src = fetchzip {
-    url = "https://github.com/mirage/io-page/archive/${version}.tar.gz";
+    url = "https://github.com/mirage/${pname}/archive/${version}.tar.gz";
     sha256 = "1rw04dwrlx5hah5dkjf7d63iff82j9cifr8ifjis5pdwhgwcff8i";
   };
 
-  buildInputs = [ ocaml findlib dune configurator ];
+  buildInputs = [ configurator ];
   propagatedBuildInputs = [ cstruct ];
 
-  inherit (dune) installPhase;
-
   meta = {
     homepage = https://github.com/mirage/io-page;
-    inherit (ocaml.meta) platforms;
     license = stdenv.lib.licenses.isc;
     description = "IO memory page library for Mirage backends";
     maintainers = with stdenv.lib.maintainers; [ vbgl ];