[GHC] #2968: add test for C trigraphs

[GHC]

#2968: add test for C trigraphs
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    Reporter:  duncan            |        Owner:                  
        Type:  task              |       Status:  new             
    Priority:  normal            |    Milestone:  6.12.1          
   Component:  Compiler          |      Version:  6.10.1          
    Severity:  normal            |   Resolution:                  
    Keywords:                    |   Difficulty:  Unknown         
    Testcase:                    |           Os:  Unknown/Multiple
Architecture:  Unknown/Multiple  |  
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Changes (by igloo):

  * milestone:  6.12 branch => 6.12.1

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2968#comment:5>
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