[GHC] #7985: Allow openFile on unknown file type

[GHC]

#7985: Allow openFile on unknown file type
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        Reporter:  singpolyma        |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Core Libraries    |              Version:  7.6.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by singpolyma):

 IODeviceType as defined in
 https://github.com/ghc/ghc/blob/master/libraries/base/GHC/IO/Device.hs

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7985#comment:7>
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