Configure Nix package names for bz2 and crypt libraries.

Required for <https://github.com/NixOS/nixpkgs/pull/2264>.
Add post-processing hook that disables text-icu's test suite on Darwin.

https://github.com/bos/text-icu/issues/6
https://github.com/NixOS/nixpkgs/pull/2254
gtk2hs-buildtools requires 'hashtables' build input when compiling with
GHC 7.8.2. We add that package unconditionally in a post-process hook.
hackage4nix.hs: don't try to update cabal-delete
hackage4nix.hs: don't try to update cryptol
Configure post-process hook for 'tz'.
Map system package 'jack' to 'jackaudio'.
hackage4nix: don't try update fsnotify
Add post-process hook for hfsevents.
hackage4nix.hs: ignore cryptol some more
Configure post-process hook for ghc-mod to deal with GHC 7.8.2.
release.nix: include build instructions for Hydra
Haddock no longer needs alex or happy to build.

https://github.com/NixOS/nixpkgs/issues/2481
hackage4nix.hs: ignore agda stdlib
hackage4nix.hs: don't re-generate syb-0.4.1
Configure post-process hook for HTTP library.
Configure post-process hook for QuickCheck.
Configure post-process hook for tar.
Enable test builds with GHC 6.10.4.
Configure post-process hook for syb.