code-minimap: fix darwin build (#123031)

pkgs/tools/misc/code-minimap/default.nix

@@ -1,6 +1,8 @@
 { lib
+, stdenv
 , rustPlatform
 , fetchFromGitHub
+, libiconv
 }:
 
 rustPlatform.buildRustPackage rec {
@@ -16,6 +18,8 @@ rustPlatform.buildRustPackage rec {
 
   cargoSha256 = "sha256-87aRZC4OE3UTVToHi5XDBxVqEH4oFeFR4REf69OBkIw=";
 
+  buildInputs = lib.optional stdenv.isDarwin libiconv;
+
   meta = with lib; {
     description = "A high performance code minimap render";
     homepage = "https://github.com/wfxr/code-minimap";