retroArchCores: remove

`retroArchCores` is strange: it requires a global configuration on nixpkgs, as:

```nix
nixpkgs.config.retroarch = {
  enableDolphin = true;
  enableMGBA = true;
  enableMAME = true;
};
```

To do so, we ended up declaring all available emulators on
`all-packages.nix`. Failing to do so would mean that the emulator
wouldn't be available.

However, there is a mechanism on nixpkgs that also works: overrides.
Overrides are similar on how other packages works, for example:

```nix
(retroarch.override { cores = with libretro; [ citra snes9x ]; });
```

So let's remove `retroArchCores` and leave the overrides mechanism
instead.

0 files changed, 0 insertions, 0 deletions