noweb: add useIcon boolean arg

pkgs/development/tools/literate-programming/noweb/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchFromGitHub, nawk, groff, icon-lang }:
+{ lib, stdenv, fetchFromGitHub, nawk, groff, icon-lang, useIcon ? true }:
 
 lib.fix (noweb: stdenv.mkDerivation rec {
   pname = "noweb";
@@ -22,14 +22,14 @@ lib.fix (noweb: stdenv.mkDerivation rec {
     substituteInPlace Makefile --replace 'strip' '${stdenv.cc.targetPrefix}strip'
   '';
 
-  nativeBuildInputs = [ groff ] ++ lib.optionals (!isNull icon-lang) [ icon-lang ];
+  nativeBuildInputs = [ groff ] ++ lib.optionals useIcon [ icon-lang ];
   buildInputs = [ nawk ];
 
   preBuild = ''
     mkdir -p "$out/lib/noweb"
   '';
 
-  makeFlags = lib.optionals (!isNull icon-lang) [
+  makeFlags = lib.optionals useIcon [
     "LIBSRC=icon"
     "ICONC=icont"
   ] ++ [ "CC=${stdenv.cc.targetPrefix}cc" ];

pkgs/top-level/all-packages.nix

@@ -12863,7 +12863,7 @@ in
     gconf = pkgs.gnome2.GConf;
   };
 
-  # NOTE: Override and set icon-lang = null to use Awk instead of Icon.
+  # NOTE: Override and set useIcon = false to use Awk instead of Icon.
   noweb = callPackage ../development/tools/literate-programming/noweb { };
 
   nuweb = callPackage ../development/tools/literate-programming/nuweb { tex = texlive.combined.scheme-medium; };