idris: re-generate expression with cabal2nix
hoogle-4.2.34: re-generate expression with cabal2nix
haskell-pandoc-citeproc: remove duplicate 'default.nix' file

We already have version 0.6 in 0.6.nix.
haskell-pandoc-citeproc: re-generate expression(s) with cabal2nix