fixup genodeSources update

packages/genodelabs/default.nix

@@ -103,6 +103,7 @@ let
         ''
           runHook preBuild
           export CONTRIB_DIR=$NIX_BUILD_TOP/contrib
+          export GENODE_CONTRIB_CACHE=$NIX_BUILD_TOP/contrib/cache
           export GENODE_DIR=${if dontUnpack then genodeSources else "$(pwd)"}
           for repo in $extraRepos; do
             ln -s $repo $GENODE_DIR/repos/
@@ -423,7 +424,7 @@ in makePackages // depotPackages // {
     postInstall = ''
       mv $out/lib/ld-nova.lib.so $out/lib/ld.lib.so
       mv $out/bin/nova_timer_drv $out/bin/timer_drv
-      install build/bin/core-nova.o $coreObj
+      install $BUILD_DIR/bin/core-nova.a $coreObj
     '';
     dontErisPatch = true;
   };