numdiff: fix darwin build

pkgs/tools/text/numdiff/default.nix

···
-{ lib, stdenv, fetchurl }:
+{ lib, stdenv, fetchurl, libintl }:
 
 
 stdenv.mkDerivation rec {
···
     url = "mirror://savannah/numdiff/numdiff-${version}.tar.gz";
     sha256 = "1vzmjh8mhwwysn4x4m2vif7q2k8i19x8azq7pzmkwwj4g48lla47";
   };
+
+  buildInputs = [ libintl ];
+
   meta = with lib; {
     description = ''
       A little program that can be used to compare putatively similar files
···
     homepage = "https://www.nongnu.org/numdiff/";
     license = licenses.gpl3Plus;
     maintainers = with maintainers; [];
-    platforms = platforms.gnu ++ platforms.linux;
+    platforms = platforms.unix;
   };
 }