[GHC] #11752: ghc-8.0 branch fails to build with ghc-7.8

[GHC]

#11752: ghc-8.0 branch fails to build with ghc-7.8
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           Reporter:  erikd          |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:  8.0.1
          Component:  Compiler       |           Version:  8.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Building GHC
  Unknown/Multiple                   |  failed
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 Problems with `getAllocationCounter` not being available in 7.8's
 `GHC.Conc` and ghc-7.8 not having `pure` in the prelude.

 Patch attached.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11752>
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