[GHC] #15995: Make Control.Concurrent.QSem a newtype

[GHC]

#15995: Make Control.Concurrent.QSem a newtype
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           Reporter:  chessai        |             Owner:  (none)
               Type:  feature        |            Status:  new
  request                            |
           Priority:  normal         |         Milestone:  8.6.3
          Component:                 |           Version:  8.6.2
  libraries/base                     |
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 {{{#!hs
 data QSem = QSem !(MVar (Int, [MVar ()], [MVar ()]))
 }}}

 I think this should be a newtype. The strictness annotations on the outter
 `MVar` could just be at each site where pattern matching on the `QSem`.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15995>
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