Less builds fine on Illumos.

pkgs/tools/misc/less/default.nix

···
   meta = {
     homepage = http://www.greenwoodsoftware.com/less/;
     description = "A more advanced file pager than ‘more’";
-    platforms = stdenv.lib.platforms.linux ++ stdenv.lib.platforms.darwin;
+    platforms = stdenv.lib.platforms.unix;
     maintainers = [ stdenv.lib.maintainers.eelco ];
   };
 }