[GHC] #9230: Make -fwarn-tabs the default

[GHC]

#9230: Make -fwarn-tabs the default
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              Reporter:  dfeuer      |            Owner:  mlen
                  Type:  feature     |           Status:  new
  request                            |        Milestone:  7.10.1
              Priority:  normal      |          Version:  7.8.2
             Component:  Compiler    |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Easy (less than 1
  Unknown/Multiple                   |  hour)
       Type of failure:              |       Blocked By:
  None/Unknown                       |  Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by hvr):

 I've emailed the developers whose name show up in Phab:P22 suggesting to
 remove tabs in the modules they had touched last according to Git.
 Hopefully, the Haskell modules in `ghc.git` will be tab-free soon...

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9230#comment:13>
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