Snippets for ccache 4.13.6 from Nix aarch64-darwin

Sourced from https://hydra.nixos.org/log/xdx8gary3w6wyv65jchfrpwjmklyvw1w-ccache-4.13.6.drv.

• /nix/var/nix/builds/nix-56511-2131222656/source/src/ccache/util/file.cpp:107:1: warning: unused function 'copy_fd' [-Wunused-function]
    107 | copy_fd(int src_fd, int dst_fd)
        | ^~~~~~~