patch applied (ghc): Fix bug in cast optimisation; fixes Trac #995

[Simon Peyton Jones]

Wed Jan  3 07:35:30 PST 2007  simonpj at microsoft.com
  * Fix bug in cast optimisation; fixes Trac #995
  
  There was a plain bug in the cast-optimiation code -- a call to
  splitCoercionKind_maybe instead of coercionKind!  Result was that
  we missed useful opportunities to move casts around.  Trac #995
  is an example, but I bet there are more.
  

    M ./compiler/simplCore/Simplify.lhs -13 +14