Setup ccache - save the planet

[arntanguy]

Let's save the planet and my sanity and enable ccache

Based on:

• https://nixos.wiki/wiki/CCache
• https://gitlab.linphone.org/BC/public/linphone-sdk/-/blob/7d9c53d68a3f26d3a35c38105520e1dc1a388817/flake.nix

[arntanguy]

@nim65s This seems to work for standard derivations declared wiith stdenv.mkDerivation but does not work with the buildRosPackage wrapper. I'm not sure I really understand how this ccacheWrapper wizardry works, it somehow sets up ccache and overrides stdenv with ccacheStdenv. I assume that the ros issue is that buildRosPackage does not directly depend on stdenv? Any idea how to make it work?