[GHC] #12707: Add contributed performance testcase

[GHC]

#12707: Add contributed performance testcase
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           Reporter:  bgamari        |             Owner:  bgamari
               Type:  task           |            Status:  new
           Priority:  normal         |         Milestone:  8.2.1
          Component:  Compiler       |           Version:  8.0.1
           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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 phadej was kind enough to offer a compile-time performance testcase. Add
 it to the testsuite or perhaps nofib.

 https://gist.github.com/phadej/554c2cc7e06b98142dc0fbadb6d3a47f

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12707>
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