haskell: add csv-conduit, packdeps

csv-conduit is a CSV library using conduit (streams)

packdeps is an executable to compare Haskell dependencies to latest
available versions
Merge pull request #5402 from bergey/haskell-csv-conduit-packdeps

haskell: add csv-conduit, packdeps
Haskell NG.
hackage-packages.nix: manual edits that need to backported to cabal2nix!
haskell-modules: implement shared library linking, check phase, object splitting, etc.
hackage-packages.nix: manually disable test suite for 'setenv'
haskell-generic-builder: re-write the way build inputs are found

Every package has a directory $out/nix-support/${ghc.name}-package.conf.d that
contains the transitive closure of all build inputs required to build this
package (and run the test suite).
hackage-packages.nix: manually disable haddock phase of 'hspec-discover'
hackage-packages.nix: manually disable test suite for 'doctest'
haskell-generic-builder: set $GHC_PACKAGE_PATH to fix doctest-style unit tests
haskell-generic-builder: re-enable support for running jailbreak-cabal
hackage-packages.nix: manually jailbreak ChasingBottoms
haskell-generic-builder: add 'hasActiveLibrary' convenience variable
haskell-generic-builder: run haddock only if the package contains a library
haskell-generic-builder: prepend "haskell-" to Haskell library names
haskell-generic-builder: re-enable code that fixed dynamically linked executables on Darwin
hackage-packages.nix: manually fix network-uri
haskell-modules: implement overrideArgs method to re-write derivation attributes
ghc-head requires ghc > 7.6.x to build
Fix bootstrapping for lots of GHC versions.