cloc: fix sourceRoot

pkgs/tools/misc/cloc/default.nix

···
     sha256 = "1ihma4f6f92jp1mvzr4rjrgyh9m5wzrlxngaxfn7g0a8r2kyi65b";
   };
 
-  sourceRoot = "cloc-${version}-src/Unix";
+  sourceRoot = "source/Unix";
 
   buildInputs = [ makeWrapper perl AlgorithmDiff RegexpCommon ];