data/fonts: cleanup

* make font derivations fixed-output where applicable
 * fix dead links
 * `stdenv.lib` -> `lib` where `stdenv` is not involved
 * remove `meta.platforms = [ unix ]` and `meta.platforms = [ linux ]` because the restriction has no sense for data packages

pkgs/data/fonts/comfortaa/default.nix

@@ -1,4 +1,4 @@
-{stdenv, fetchzip}:
+{ lib, fetchzip }:
 
 let
   version = "3.001";
@@ -8,13 +8,12 @@ in fetchzip rec {
   url = "https://orig00.deviantart.net/40a3/f/2017/093/d/4/comfortaa___font_by_aajohan-d1qr019.zip";
   postFetch = ''
     mkdir -p $out/share/fonts $out/share/doc
-    unzip -l $downloadedFile
     unzip -j $downloadedFile \*.ttf                        -d $out/share/fonts/truetype
     unzip -j $downloadedFile \*/FONTLOG.txt \*/donate.html -d $out/share/doc/${name}
   '';
   sha256 = "0z7xr0cnn6ghwivrm5b5awq9bzhnay3y99qq6dkdgfkfdsaz0n9h";
 
-  meta = with stdenv.lib; {
+  meta = with lib; {
     homepage = http://aajohan.deviantart.com/art/Comfortaa-font-105395949;
     description = "A clean and modern font suitable for headings and logos";
     license = licenses.ofl;