gnu: ghc-haddock-library: Update to 1.7.0.

gnu: ghc-haddock-library: Update to 1.7.0.

The new source tarball does not have bundled dependencies, so it does
not need to be patched.

* gnu/packages/haskell-xyz.scm (ghc-haddock-library): Update to 1.7.0.
[source]: Remove 'patches', 'modules' and 'snippet'.
[arguments]: Update the 'relax-test-suite-dependencies' phase to allow
newer versions of 'hspec' and 'QuickCheck'; remove the
'add-examples-directory' phase.
* gnu/packages/patches/ghc-haddock-library-unbundle.patch: Delete file.
* gnu/local.mk: Remove it.