SDL_ttf: fix build on darwin

Without it, the build failed with:

Undefined symbols for architecture arm64:
  "_iconv", referenced from:
      _SDL_main in showfont.o
  "_iconv_close", referenced from:
      _SDL_main in showfont.o
  "_iconv_open", referenced from:
      _SDL_main in showfont.o

Signed-off-by: Ihar Hrachyshka <[email protected]>

Author: booxter

pkgs/by-name/sd/SDL_ttf/package.nix

@@ -33,6 +33,8 @@ stdenv.mkDerivation (finalAttrs: {
     (lib.enableFeature enableSdltest "sdltest")
   ];
 
+  env.NIX_LDFLAGS = lib.optionalString stdenv.hostPlatform.isDarwin "-liconv";
+
   strictDeps = true;
 
   passthru.updateScript = unstableGitUpdater {