[GHC] #15718: Build panic on ghc-8.6.1 under FreeBSD when using -fllvm

[GHC]

#15718: Build panic on ghc-8.6.1 under FreeBSD when using -fllvm
-------------------------------------+-------------------------------------
        Reporter:  gwright           |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  high              |            Milestone:  8.8.1
       Component:  Compiler (LLVM)   |              Version:  8.6.1
      Resolution:                    |             Keywords:
Operating System:  FreeBSD           |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D5448
       Wiki Page:                    |
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Changes (by bgamari):

 * status:  new => patch
 * differential:   => Phab:D5448


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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15718#comment:6>
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