[GHC] #16206: Run Haddock's test suite in CI

[GHC]

#16206: Run Haddock's test suite in CI
-------------------------------------+-------------------------------------
        Reporter:  sjakobi           |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Test Suite        |              Version:  8.6.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by harpocrates):

 This should be pretty achievable. In particular, the `html-test`, `latex-
 test`, `hypsrc-test`, and `hoogle-test` testsuites don't have large
 dependencies. In fact, the only extra library we would need to build would
 be the very stable and small `xml`.

 If someone with some experience hacking on GHC's testsuite could advise,
 I'd be happy to take this on.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16206#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler