ocamlPackages.ocaml_oasis: fix build

Add missing pre/post hooks - preConfigure is now required,
as findlib sets a necessary preConfigure hook

pkgs/development/tools/ocaml/oasis/default.nix

@@ -18,9 +18,21 @@ stdenv.mkDerivation {
       ocaml findlib ocamlbuild ocamlmod ocamlify
     ];
 
-  configurePhase = "ocaml setup.ml -configure --prefix $out";
-  buildPhase     = "ocaml setup.ml -build";
-  installPhase   = "ocaml setup.ml -install";
+  configurePhase = ''
+    runHook preConfigure
+    ocaml setup.ml -configure --prefix $out
+    runHook postConfigure
+  '';
+  buildPhase = ''
+    runHook preBuild
+    ocaml setup.ml -build
+    runHook postBuild
+  '';
+  installPhase = ''
+    runHook preInstall
+    ocaml setup.ml -install
+    runHook postInstall
+  '';
 
   meta = with lib; {
     homepage = "http://oasis.forge.ocamlcore.org/";