[GHC] #8496: Minor typos in STM.c

[GHC]

#8496: Minor typos in STM.c
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       Reporter:  aske                     |             Owner:
           Type:  bug                      |            Status:  new
       Priority:  lowest                   |         Milestone:
      Component:  Compiler                 |           Version:  7.6.3
       Keywords:                           |  Operating System:
   Architecture:  Unknown/Multiple         |  Unknown/Multiple
     Difficulty:  Easy (less than 1 hour)  |   Type of failure:
     Blocked By:                           |  None/Unknown
Related Tickets:                           |         Test Case:
                                           |          Blocking:
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 STM.c has a few small typos in the description.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8496>
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