patch applied (ghc): Fix checkHiBootIface for instances declared in hs-boot files

[Simon Peyton Jones]

Wed Mar 21 07:04:24 PDT 2007  simonpj at microsoft.com
  * Fix checkHiBootIface for instances declared in hs-boot files
  
  Hs-boot files can contain instance declarations, but Duncan used this feature
  for the first time today, and it didn't quite work.  I'm not sure whether
  it worked before; anyway it does now.
  
  The point is that the hs-boot file advertises an instance for, say, Num Int,
  with the arbitrary name $fx1.  The main module declares Num Int, and gives
  it the name, say, $f3.  So we need to generate a declaration
  	$fx1 = $f3
  to make it all line up.  And (this is the bit that was wrong) we need
  to make that new binding visible to imported unfoldings that mention
  $fx1.
  

    M ./compiler/typecheck/TcRnDriver.lhs -7 +17