deps: Try to print the dependency cycle in error message

deps: Try to print the dependency cycle in error message

Instead of:

*** error: function:wrap:6:0: adding fedora-rebuild ("ocaml-odoc") creates a dependency cycle

it now prints:

*** error: function:wrap:4:0: dependency cycle: fedora-rebuild ("ocaml-odoc") -> fedora-rebuild ("ocaml-mdx") -> fedora-rebuild ("ocaml-odoc-parser") -> fedora-rebuild ("ocaml-ppx-expect") -> fedora-rebuild ("ocaml-ppx-inline-test") -> fedora-rebuild ("ocaml-time-now") -> fedora-rebuild ("ocaml-ppx-base") -> fedora-rebuild ("ocaml-ppx-js-style") -> fedora-rebuild ("ocaml-octavius") -> fedora-rebuild ("ocaml-odoc")