patch applied (ghc): Add import facility to cmm parser

[Simon Marlow]

Fri Jul 13 14:08:45 PDT 2007  Clemens Fruhwirth <clemens at endorphin.org>
  * Add import facility to cmm parser
  
  The cmm parser classified all unknown variables as imported. This
  behaviour is not changed with this patch. Explicitly imported
  variables get a different internal label type, namely ForeignLabel
  instead of RtsLabel. In PIC compilation, the NCG creates dynamic
  access for ForeignLabel, while RtsLabel are not treated as PIC when
  -package rts. Hence, putting explicit imports into cmm files enables
  the NCG to distinguish between RTS-external and RTS-internal symbols,
  and create the appropriate code.

    M ./compiler/cmm/CmmParse.y -1 +8