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/mph-2b-damase/default.nix

@@ -1,4 +1,4 @@
-{stdenv, fetchzip}:
+{ lib, fetchzip }:
 
 fetchzip {
   name = "MPH-2B-Damase-2";
@@ -13,6 +13,5 @@ fetchzip {
   sha256 = "0yzf12z6fpbgycqwiz88f39iawdhjabadfa14wxar3nhl9n434ql";
 
   meta = {
-    platforms = stdenv.lib.platforms.unix;
   };
 }