gnu: ghc-haddock-library: Update to 1.5.0.1.

* gnu/packages/patches/ghc-haddock-library-unbundle.patch: New file.
* gnu/packages/haskell.scm (ghc-haddock-library): Update to 1.5.0.1.
[source]: Add the patch; add a snippet to remove the bundled library.
[arguments]: Add a phase to relax test suite dependency constraints and
another to add a missing directory required for tests.
[native-inputs]: Add ghc-base-compat, ghc-optparse-applicative, and
ghc-tree-diff.

gnu/packages/haskell.scm

@@ -935,7 +935,7 @@ compute the difference between arbitrary abstract datatypes (ADTs) using
 (define-public ghc-haddock-library
   (package
     (name "ghc-haddock-library")
-    (version "1.4.3")
+    (version "1.5.0.1")
     (source
      (origin
        (method url-fetch)
@@ -945,14 +945,37 @@ compute the difference between arbitrary abstract datatypes (ADTs) using
              ".tar.gz"))
        (sha256
         (base32
-         "0ns4bpf6whmcfl0cm2gx2c73if416x4q3ac4l4qm8w84h0zpcr7p"))))
+         "1cmbg8l5xrwpliclwy3l057raypjqy0hsg1h1743ahaj8gq10b7z"))
+       (patches (search-patches
+                 "ghc-haddock-library-unbundle.patch"))
+       (modules '((guix build utils)))
+       (snippet '(begin
+                   (delete-file-recursively "vendor")
+                   #t))))
     (build-system haskell-build-system)
-    (inputs
-     `(("ghc-base-compat" ,ghc-base-compat)))
+    (arguments
+     `(#:phases
+       (modify-phases %standard-phases
+         (add-before 'configure 'relax-test-suite-dependencies
+           (lambda _
+             (substitute* "haddock-library.cabal"
+               (("base-compat\\s*\\^>= 0\\.9\\.3") "base-compat")
+               (("hspec\\s*\\^>= 2\\.4\\.4") "hspec"))))
+         ;; The release tarball does not contain the "fixtures/examples"
+         ;; directory, which is required for testing.  In the upstream
+         ;; repository, the directory exists and is populated.  Here, we
+         ;; create an empty directory to placate the tests.
+         (add-before 'check 'add-examples-directory
+           (lambda _
+             (mkdir "fixtures/examples")
+             #t)))))
     (native-inputs
-     `(("hspec-discover" ,hspec-discover)
+     `(("ghc-base-compat" ,ghc-base-compat)
        ("ghc-hspec" ,ghc-hspec)
-       ("ghc-quickcheck" ,ghc-quickcheck)))
+       ("ghc-optparse-applicative" ,ghc-optparse-applicative)
+       ("ghc-quickcheck" ,ghc-quickcheck)
+       ("ghc-tree-diff" ,ghc-tree-diff)
+       ("hspec-discover" ,hspec-discover)))
     (home-page "https://www.haskell.org/haddock/")
     (synopsis "Library exposing some functionality of Haddock")
     (description