fix tar command

overlays/cfg-if-fix.nix

···
           drv' = if pkg.name == "cfg-if" then
                    drv.overrideAttrs (old: {
                      unpackPhase = ''
-                       tar -xzf $src
+                       tar -x -z -f $src
                      '';
                    })
                  else
···
         previousOverride pkg drv';
     in
     prev.vendorCargoDeps (args // { overrideVendorCargoPackage = newOverride; });
-}
+}