patch applied (ghc): Keep the CPS pass from creating proc points due to unreachable parents.

[Michael Adams]

Sun Jul 15 09:20:03 PDT 2007  Michael D. Adams <adamsmd at cs.indiana.edu>
  * Keep the CPS pass from creating proc points due to unreachable parents.
  
  The parser/flattener will generate an extra block after an if/else 
  statement even if both branches exit the function.  So it is possible
  for the input to the CPS pass to have dead/unreachable blocks.
  
  If a dead block goes to a live block then the live block would
  have more parents than the dead block and prior to this patch
  the live block would then be identified as a proc point.
  This is fixed by adding a check to see if the parent
  has at least one owner.

    M ./compiler/cmm/CmmProcPoint.hs -2 +6