[GHC] #15042: Bump unix's version number to 2.8.0.0 in HEAD

[GHC]

#15042: Bump unix's version number to 2.8.0.0 in HEAD
-------------------------------------+-------------------------------------
           Reporter:  RyanGlScott    |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:  8.6.1
          Component:  libraries      |           Version:  8.5
  (other)                            |
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:  #15018
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 In order to perform a `unix` submodule bump (as requested in #15018),
 we'll need to deal with the fact that its major version number was bumped
 upstream to 2.8.0.0. As a result, the following boot libraries will need
 to be adjusted:

 * `Cabal` and `cabal-install`
 * `directory`
 * `haskeline`
 * `iserv-bin` (ready, in-place)
 * `process`

 Some of these can be changed in-place, while others will require
 downstream changes. I'll update this ticket as I progress.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15042>
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