Update sources

[anmonteiro]

:robot_face: Updating sources to the latest version.

Commits touching OCaml packages:

• ocamlPackages.dune_{2,3}: don't throw when evaling

• ocamlPackages.labltk: mark as broken on unsupported versions

• ocamlPackages: swap throws to meta.broken

throws no longer work with the current ci we have in nixpkgs

• release.nix: eval and build ocamlPackages

eval of ocamlPackages was broken, let's enable it to be checked by ci

• ocamlPackages:  fix eval and let ci check that it still evals (#406555)

• ocamlPackages.unionFind: small fixes

• ocamlPackages.lwt_camlp4: remove at unstable-2018-03-25

• ocamlPackages.lwt_camlp4: remove at unstable-2018-03-25 (#460861)

• ocamlPackages.nonstd: remove at 0.0.3

• ocamlPackages.nonstd: remove at 0.0.3 (#460251)

• ocamlPackages.unionFind: small fixes (#460757)

• empire-compiler: 0.4.1 -> 0.4.2 (#461487)

• empire-compiler: 0.4.1 -> 0.4.2 (#461487)

• empire-compiler: 0.4.1 -> 0.4.2 (#461487)

Diff URL: https://github.com/NixOS/nixpkgs/compare/e1ce86c3e40327779390e98edab843d4a1cc9224...66d930cb8792aea66f1bb2562f26f08d2ce8c3db