Fri Aug 11 13:53:24 EDT 2006  Manuel M T Chakravarty <chak@cse.unsw.edu.au>
  * Remove argument variance info of tycons
  - Following SPJ's suggestion, this patch removes the variance information from
    type constructors.  This information was computed, but never used.
  
  ** WARNING: This patch changes the format of interface files **
  **          You will need to rebuild from scratch.           **