patch applied (ghc): Breakpoints: get the names of the free variables right

[Simon Marlow]

Tue Apr 24 04:32:02 PDT 2007  Simon Marlow <simonmar at microsoft.com>
  * Breakpoints: get the names of the free variables right
  
  Previously we relied on the names of the Ids attached to a tick being
  the same as the names of the original variables in the source code.
  Sometimes this worked, sometimes it didn't because the simplifier
  would inline away the Id.  So now we do this properly and retain the
  original OccNames from the source code for each breakpoint, and use
  these to construct the new Ids when we stop.
  
  Doing this involved moving the tracking of in-scope variables from the
  desugarer to the coverage pass.

    M ./compiler/deSugar/Coverage.lhs -66 +104
    M ./compiler/deSugar/DsArrows.lhs -2 +2
    M ./compiler/deSugar/DsExpr.lhs -11 +6
    M ./compiler/deSugar/DsGRHSs.lhs -11 +4
    M ./compiler/deSugar/DsMonad.lhs -17 +2
    M ./compiler/deSugar/DsUtils.lhs -9 +8
    M ./compiler/hsSyn/HsBinds.lhs -1 +1
    M ./compiler/hsSyn/HsExpr.lhs -2 +3
    M ./compiler/main/GHC.hs -19 +39
    M ./compiler/main/HscTypes.lhs +3