iosevka: remove dependency on otfcc

As of Iosevka 3.7.0, otfcc is no longer used.  I haven't checked if
the situation has changed since [2017] but this should make Iosevka
available on aarch64-linux and *-darwin.

[2017]: https://github.com/NixOS/nixpkgs/pull/31835#issuecomment-347048242

pkgs/data/fonts/iosevka/default.nix

@@ -1,5 +1,5 @@
 { stdenv, lib, pkgs, fetchFromGitHub, nodejs, nodePackages, remarshal
-, ttfautohint-nox, otfcc
+, ttfautohint-nox
 
 # Custom font set options.
 # See https://github.com/be5invis/Iosevka#build-your-own-style
@@ -51,7 +51,6 @@ stdenv.mkDerivation rec {
     nodejs
     nodeIosevka
     remarshal
-    otfcc
     ttfautohint-nox
   ];