convertlit: disable format hardening

pkgs/tools/text/convertlit/default.nix

@@ -1,22 +1,24 @@
-{stdenv, fetchurl, unzip, libtommath}:
+{stdenv, fetchzip, libtommath}:
 
 stdenv.mkDerivation {
   name = "convertlit-1.8";
-  
-  src = fetchurl {
+
+  src = fetchzip {
     url = http://www.convertlit.com/convertlit18src.zip;
-    sha256 = "1fjpwncyc2r3ipav7c9m7jxy6i7mphbyqj3gsm046425p7sqa2np";
+    sha256 = "182nsin7qscgbw2h92m0zadh3h8q410h5cza6v486yjfvla3dxjx";
+    stripRoot = false;
   };
 
-  buildInputs = [unzip libtommath];
+  buildInputs = [libtommath];
 
-  sourceRoot = ".";
+  hardeningDisable = [ "format" ];
 
   buildPhase = ''
     cd lib
     make
     cd ../clit18
-    substituteInPlace Makefile --replace ../libtommath-0.30/libtommath.a -ltommath
+    substituteInPlace Makefile \
+      --replace ../libtommath-0.30/libtommath.a -ltommath
     make
   '';