adds buildable expe drv

pkgs/default.nix

@@ -204,6 +204,10 @@ let
         zymake
       ];
       buildPhase = "zymake ${experiments-src}/experiments/zymakefile";
+      installPhase = ''
+        mkdir -p $out
+        cp -r o/* $out
+      '';
     });
 
     analysis =