[cvs-nhc98] patch applied (hat): Change internal representation of export decls.

[Malcolm Wallace]

Wed Aug  8 07:58:19 PDT 2001  malcolm
  * Change internal representation of export decls.
  
    * Previously, the two cases
          module M where
          module M () where
      were not distinguished!
      The former should export everything, the latter nothing.
  
    * In the old representation both cases were [] :: [Export id].
  
    * In the new representation :: Maybe [Export id],
      Nothing means nothing, and Just [] means everything.
      (Just [...] gives an explicit list of export decls much as before.)

    M ./src/compiler98/AuxFile.hs -6 +19
    M ./src/compiler98/AuxLabelAST.hs -3 +5
    M ./src/compiler98/Need.hs -1 +3
    M ./src/compiler98/Parse2.hs -3 +3
    M ./src/compiler98/PreImport.hs -2 +7
    M ./src/compiler98/PrettySyntax.hs -6 +4
    M ./src/compiler98/Syntax.hs -1 +1
    M ./src/compiler98/TraceTrans.hs -2 +6
    M ./src/hattrans/AuxFile.hs -6 +19
    M ./src/hattrans/AuxLabelAST.hs -3 +5
    M ./src/hattrans/TraceTrans.hs -2 +6