pkgsMusl, pkgsi686Linux, pkgsStatic: fix infinite recursion with overlays

Consider example:

$ nix-instantiate ./nixos -A system --arg configuration '
    {
      boot.isContainer = true;
      nixpkgs.overlays = [ (self: super: {
        nix = self.pkgsStatic.nix;
      }) ];
    }'

When resolving package through overlays, we figure out that

  nix == self.pkgsStatic.nix
  =>
  nix == (import <nixpkgs> { inherit overlays; }).nix
  =>
  nix == (import <nixpkgs> { overlays = [(self: super: { nix = self.pkgsStatic.nix; })];}).nix

and we enter infinite recursion of nixpkgs evaluations.

The proper fix should terminate recursion by assigning self fixpoint
to inner custom package set. But I get infinite recursion somehow, so
I use `super`. It is less correct modulo deep custom overrides, but behaves
correctly for simple cases and doesn't OOM evaluator.

Fixes https://github.com/NixOS/nixpkgs/issues/57984