[GHC] #15278: Add -Werror=compat, enable it in the testsuite

[GHC]

#15278: Add -Werror=compat, enable it in the testsuite
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        Reporter:  int-index         |                Owner:  (none)
            Type:  task              |               Status:  closed
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler          |              Version:
      Resolution:  fixed             |             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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Changes (by bgamari):

 * status:  new => closed
 * resolution:   => fixed


Comment:

 I believe that should finish this.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15278#comment:4>
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