Snippets for jsoncpp 1.9.8 from Nix aarch64-darwin

Sourced from https://hydra.nixos.org/log/igk0z0lvi9ly9pjr1fy6kc4x7v8xbdy3-jsoncpp-1.9.8.drv.

• /nix/var/nix/builds/nix-20433-2587017738/source/src/jsontestrunner/main.cpp:63:31: warning: implicit conversion changes signedness: 'long' to 'unsigned long' [-Wsign-conversion]
     63 |   auto buffer = new char[size + 1];
        |                 ~~~      ~~~~~^~~